JP2017215124A - Waste incineration device, waste incineration method, burned ash handling system, and burned ash treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste incineration device, a waste incineration method, a burned ash handling system, and a burned ash treatment method capable of further improving the efficiency of the detoxification treatment while it is possible to apply the detoxification treatment which restricts the elution of metals contained in the burned ash to the whole incineration ash.SOLUTION: A fire grate type waste incineration device that has a combustion furnace 1 for burning waste whose combustion chamber including a dehydration fire grate 5a, a combustion fire grate 5b, and a post combustion fire grate 5c, and primary air supply means II for supplying the primary air to the below of each fire grate and that comprises: a circulation exhaust gas supply means IV for supplying a part of the exhaust gas of the combustion furnace 1 to the below of the dehydration fire grate 5a, the combustion fire grate 5b, and the post combustion fire grate 5c; and oxygen concentration adjusting means for adjusting the oxygen concentration of the mixed gas of the primary air and the circulation exhaust gas to be supplied to the below of respective fire grates.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a grate-type waste incineration apparatus and a waste incineration method for incinerating waste such as municipal waste, and an incineration ash treatment apparatus for detoxifying harmful substances in incineration ash discharged from a waste incinerator And an incineration ash treatment method.

  Most of the incineration residue generated when incinerating waste such as municipal waste and industrial waste is disposed of in landfills. However, in recent years, it has become difficult to secure a landfill site, and there is a demand for reducing the amount of landfill. For this reason, attempts have been made to effectively use incineration residue (hereinafter referred to as “incineration ash”) discharged from a waste incinerator as a resource to reduce the amount of landfill disposal.

  However, incineration ash contains harmful substances, especially heavy metals. Therefore, when the amount of elution of heavy metals from the incinerated ash is greater than or equal to the reference value, it is difficult to use it as a resource as it is. In order to cope with such a situation, in order to use the incinerated ash having the above-described properties as a resource, the incineration ash is processed by removing heavy metals from the incinerated ash or by stabilizing the heavy metals. The amount of elution from the solution must be below the reference value. In addition, among heavy metals contained in incineration ash, since the content of lead is particularly large, heavy metals to be treated are mainly lead.

  Regarding the insolubilization of lead as heavy metals in incineration ash, the following is known.

(1) The lead contained in the incineration ash has a property that the solubility in water is lowered by reacting the lead with carbon dioxide to produce a carbonate. Specifically, by changing from lead oxide PbO to lead carbonate PbCO ₃ , the solubility in water is 107 mg / l with lead oxide, but with lead carbonate it is greatly reduced to 2.5 mg / l, making it insoluble. Become.

(2) Incineration ash is basic and the pH of the eluate is high. Regarding the pH of the incineration ash, the calcium oxide CaO or calcium hydroxide Ca (OH) ₂ contained in the incineration ash is reacted with carbon dioxide to form calcium carbonate CaCO ₃ , thereby reducing the pH of the incineration ash to that of heavy metals. It is also made to be a low pH hardly soluble region showing Among heavy metals in incineration ash, lead with a high content is an amphoteric metal, and the incineration ash showing strong basicity is subjected to a treatment that lowers the pH to make it a poorly soluble region, thereby elution of lead. The amount can be reduced.

  In this way, (1) lead carbonate is generated by carbonation reaction of heavy metals such as lead to make it hardly soluble, and (2) the pH of the incinerated ash is lowered to make it hardly soluble. Thus, heavy metals can be made slightly soluble, elution of heavy metals from the incineration ash can be suppressed, and the heavy metal elution standards in the soil environment standard, which is a reference value when using the incineration ash as a civil engineering material, can be satisfied.

  The reference value for the lead elution amount of incineration ash at present is a lead elution amount of 0.01 mg / l when effectively used as a resource. For this reason, when incineration ash is used, the incineration ash must be treated to make it less than these reference values.

  Under the circumstances where the insolubilization treatment of heavy metals contained in incineration ash is known, as a detoxification treatment method for incineration ash, paragraphs [0040] to [0042] of Patent Document 1 and FIG. The method disclosed in is known. In the method of detoxifying heavy metals of incineration ash disclosed in Patent Document 1, combustion exhaust gas from a waste incinerator is extracted from a flue by a blower and mixed with high-temperature combustion gas generated in a hot air generating furnace After being heated to a predetermined temperature in the range of 400 ° C. to 600 ° C., it is introduced into the post-combustion grate, and the exhaust gas from the waste incinerator is vented to the incineration ash on the post-combustion grate. As a result, the components of the incineration ash react with the carbon dioxide in the exhaust gas, and lead carbonate is generated by the carbonation reaction of heavy metals such as lead to make it insoluble, and the pH of the incineration ash is lowered. The insolubilization process of the incineration ash which suppresses the elution of heavy metals from the incineration ash is also performed by making the hardly soluble region.

JP2003-340397

  However, in the method disclosed in Patent Document 1, when the particles of the incinerated ash on the post-combustion grate are agglomerated and fused and have a large diameter, only the surface of the incinerated ash particles Since the reaction does not proceed, there is a problem that sufficient detoxification treatment cannot be performed on the entire incinerated ash, and the efficiency of the detoxification treatment is low. Moreover, in order to generate the high-temperature combustion gas mixed with the combustion exhaust gas, a hot air generating furnace is additionally required, and there is a problem that equipment costs and operation costs increase.

  In view of such circumstances, the present invention can perform a detoxification treatment for suppressing the elution of heavy metals of incineration ash to the entire incineration ash, and further improve the efficiency of the detoxification treatment. It is an object to provide an incinerator, a waste incineration method, an incineration ash treatment device, and an incineration ash treatment method.

  According to the present invention, the above-mentioned problems are a waste incinerator according to the first invention, a waste incineration method according to the second invention, an incineration ash treatment apparatus according to the third invention, and an incineration ash according to the fourth invention. It is solved by the processing method.

<First invention>
A combustion chamber of an incinerator that burns waste is provided with a dry grate, a combustion grate, and a post-combustion grate, and is provided with primary air supply means for supplying primary air below each grate. In the lattice-type waste incinerator,
Circulating exhaust gas supply means for supplying a part of the exhaust gas from the incinerator to the lower side of the dry grate, the combustion grate and the post-combustion grate, and mixing of the primary air and the circulating exhaust gas supplied to the lower side of the respective grate A grate-type waste incinerator having oxygen concentration adjusting means for adjusting the oxygen concentration of gas.

  In the present invention, the oxygen concentration adjusting means sets the oxygen concentration of the mixed gas supplied below the dry grate and the combustion grate to 14 to 18 vol%, and the oxygen concentration of the mixed gas supplied below the post-combustion grate is 2 It is preferable to adjust to -14 vol%, respectively.

  In the present invention, there is further provided an incineration ash layer temperature control means for controlling the temperature of the incinerated ash layer on the post-combustion grate to a predetermined temperature, and the incineration ash layer temperature control means is supplied below the post-combustion grate. It is preferable to control at least one of the primary air supply amount and the circulating exhaust gas supply amount. Moreover, it is preferable to control the temperature of the incinerated ash layer on the post-combustion grate within a range of 400 to 700 ° C.

<Second invention>
In a waste incineration method provided in a combustion chamber of an incinerator for combusting waste to supply primary air below the respective grate of a dry grate, a combustion grate and a post-combustion grate,
A part of the exhaust gas from the incinerator is supplied below the dry grate, combustion grate and post-combustion grate, and the oxygen concentration in the mixed gas of primary air and circulating exhaust gas supplied below each grate Waste incineration method characterized by adjusting

  In the present invention, the oxygen concentration of the mixed gas supplied below the dry grate and the combustion grate is adjusted to 14-18 vol%, and the oxygen concentration of the mixed gas supplied below the post-combustion grate is adjusted to 2-14 vol%, respectively. It is preferable to do.

  In the present invention, the temperature of the incinerated ash layer on the post-combustion grate is preferably controlled in the range of 400 to 700 ° C.

<Third invention>
A combustion chamber of an incinerator that burns waste is provided with a dry grate, a combustion grate, and a post-combustion grate, and is provided with primary air supply means for supplying primary air below each grate. A device for treating incineration ash generated by burning waste in a grid-type waste incinerator,
Circulating exhaust gas supply means for supplying a part of the exhaust gas from the incinerator to the lower side of the dry grate, the combustion grate and the post-combustion grate, and mixing of the primary air and the circulating exhaust gas supplied to the lower side of the respective grate An incineration ash treatment apparatus comprising oxygen concentration adjusting means for adjusting the oxygen concentration of a gas.

  In the present invention, the oxygen concentration adjusting means sets the oxygen concentration of the mixed gas supplied below the dry grate and the combustion grate to 14 to 18 vol%, and the oxygen concentration of the mixed gas supplied below the post-combustion grate is 2 It is preferable to adjust to -14 vol%, respectively.

  In the present invention, there is further provided an incineration ash layer temperature control means for controlling the temperature of the incinerated ash layer on the post-combustion grate to a predetermined temperature, and the incineration ash layer temperature control means is supplied below the post-combustion grate. It is preferable to control at least one of the primary air supply amount and the circulating exhaust gas supply amount. Moreover, it is preferable to control the temperature of the incinerated ash layer on the post-combustion grate within a range of 400 to 700 ° C.

<Fourth Invention>
Grate provided with primary air supply means for supplying primary air to the lower side of each of the dry grate, combustion grate and post-combustion grate provided in the combustion chamber of the incinerator for burning waste A method for treating incineration ash generated by burning waste using a waste incinerator,
A part of the exhaust gas from the incinerator is supplied below the dry grate, combustion grate and post-combustion grate, and the oxygen concentration in the mixed gas of primary air and circulating exhaust gas supplied below each grate A method for treating incinerated ash, characterized by adjusting the ash.

  In the present invention, the oxygen concentration of the mixed gas supplied below the dry grate and the combustion grate is adjusted to 14-18 vol%, and the oxygen concentration of the mixed gas supplied below the post-combustion grate is adjusted to 2-14 vol%, respectively. It is preferable to do.

  In the present invention, the temperature of the incinerated ash layer on the post-combustion grate is preferably controlled in the range of 400 to 700 ° C.

  As described above, when the incinerated ash is detoxified by supplying carbon dioxide in the circulating exhaust gas to the incinerated ash on the post-combustion grate and bringing it into contact with the incinerated ash, In addition to the dry grate and the waste on the combustion grate, it was also supplied to the waste grate. Incineration ash particles are kept in a small particle size without agglomeration and fusion, and contact with carbon dioxide in the circulating exhaust gas on the post-combustion grate with sufficient contact area to ensure detoxification It becomes.

1 is a schematic configuration diagram of a waste incinerator according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows the overall configuration of a waste incinerator according to the present embodiment. This waste incinerator is connected to an incinerator I with a primary air supply means II, a subsequent apparatus III, and a circulating exhaust gas supply means IV. Has been configured. The apparatus according to the present embodiment also includes a mixed gas oxygen concentration adjusting means constituted by a part of the primary air supply means and a part of the circulating exhaust gas supply means, in addition to the above devices and means. Hereinafter, the incinerator I, the primary air supply means II, the subsequent apparatus III, the circulating exhaust gas supply means IV, and the mixed gas oxygen concentration adjusting means will be described.

  The incinerator I has, for example, a combustion chamber 2 for burning waste such as industrial waste and household waste in the furnace body 1, and an upstream side in the flow direction of waste in the combustion chamber 2 (left side in FIG. 1). The waste inlet 3 for introducing waste into the combustion chamber 2 and the downstream of the combustion chamber 2 in the waste flow direction (the right side in FIG. 1) are connected in series. A grate-type incinerator including a secondary combustion chamber 4. In the secondary combustion chamber 4 connected to the combustion chamber 2, the unburned portion (unburned gas) of the combustible gas in the combustion gas generated in the combustion chamber 2 is burned (secondary combustion).

  At the bottom of the combustion chamber 2, there is provided a grate (stoker) 5 that burns while moving the waste. The grate 5 includes a dry grate 5a that forms a dry zone, a combustion grate 5b that forms a combustion zone, and a post-combustion fire that forms a post-combustion zone from the side closer to the waste inlet 3, that is, from the upstream side. It is provided in the order of the lattice 5c, and a waste layer is mainly formed on the dry grate 5a and the combustion grate 5b, and an incineration ash layer is formed in the downstream portion of the post-combustion grate.

  In the dry grate 5a, waste is mainly dried and ignited. In the combustion grate 5b, waste is thermally decomposed and partially oxidized, and the combustible gas and solid matter generated by the thermal decomposition are combusted. When the combustible gas burns, a flame is formed. On the post-combustion grate 5c, soot combustion is performed to completely burn the unburned solids in the unburned waste, and no flame is generated when the solids in the waste burn. Burn. As a result, a layer of incinerated ash after complete combustion is formed on the downstream portion (the right half in FIG. 1) of the post-combustion grate 5c. The incinerated ash is dropped and discharged from the ash discharge unit 6.

  The primary air supply means II is provided with a wind box provided below the dry grate 5a, the combustion grate 5b and the post-combustion grate 5c in the combustion chamber 2, and a blower 7 for sending primary air to each wind box. Is provided. The primary air for combustion supplied by the blower 7 is supplied to each wind box through the primary air supply line 8, and is supplied into the combustion chamber 2 through each grate 5a, 5b, 5c. The primary air supply line 8 has branch lines 8a, 8b, 8c to the grate 5a, 5b, 5c, and dampers or valves 9a, 9b, 9c as flow rate adjusting mechanisms are provided on the branch lines. Yes. The primary air for combustion is used for drying and burning the waste on the grate 5a, 5b, 5c, as well as cooling the grate 5a, 5b, 5c and agitating the waste.

  The succeeding apparatus III connected to the combustion furnace I includes a boiler 10 as a heat recovery system that generates heat by heat exchange with the exhaust gas discharged from the incinerator I, and generates heat with the boiler 10. And a chimney 12 for releasing the exhaust gas removed by the bag filter 11 into the atmosphere.

  In the present embodiment, a circulating exhaust gas supply means IV is further provided. The circulating exhaust gas supply means IV includes an exhaust gas duct (smoke) on the outlet side of the bag filter 11 and a dry fire grate 5a, a combustion grate 5b, and a wind box below the rear combustion grate 5c through a circulating exhaust gas supply line 13. The exhaust gas after dust removal by the bag filter 11 is sent to each wind box as a circulating exhaust gas. The circulating exhaust gas supply line 13 has branch lines 13a, 13b, 13c to the grate 5a, 5b, 5c. Each branch line 13a, 13b, 13c is provided with dampers or valves 14a, 14b, 14c for adjusting the flow rate. The circulating exhaust gas supply line 13 is provided with a blower 15.

  Thus, the primary air and the circulating exhaust gas are supplied to the wind boxes under the respective grate 5a, 5b, 5c with their respective flow rates adjusted, supplied as mixed gas to the grate 5a, 5b, 5c, waste, Aerated by incineration ash. The configuration of the line for supplying the primary air and the circulating exhaust gas to the wind box is not limited to the illustrated one, and can be appropriately selected depending on the scale, shape, application, etc. of the incinerator.

  In this embodiment, the oxygen concentration of the mixed gas of the primary air from the primary air supply means II and the circulating exhaust gas from the circulating exhaust gas supply means IV is adjusted by the oxygen concentration adjusting means. The oxygen concentration adjusting means includes the blower 15 of the circulating exhaust gas supply means IV, dampers or valves 14a, 14b and 14c, and the damper or valves 9a, 9b and 9c of the primary air supply means II. Thus, the oxygen concentration of the mixed gas is adjusted by adjusting the supply amount of the circulating exhaust gas from the blower 15 and the respective opening degrees of the dampers or valves 14a, 14b, 14c and the dampers or valves 9a, 9b, 9c.

  Next, the adjustment by the oxygen concentration adjusting means will be described in detail.

  The oxygen concentration adjusting means lowers the oxygen concentration of the mixed gas supplied to the dry grate 5a and the combustion grate 5b to less than 21 vol% when supplying the conventional air, and supplies the conventional gas with the flow rate of the mixed gas. More than the flow rate when doing. Thus, by reducing the oxygen concentration, the reaction (combustion) between waste and oxygen is slowed down, and by increasing the flow rate, the amount of nitrogen that does not contribute to waste combustion is increased to suppress excessive temperature rise. Therefore, make sure that the temperature atmosphere at which the waste on the grate burns does not become excessively high.

  Thus, the incinerated ash produced by burning the waste is not excessively heated in the above temperature atmosphere. As a result, the incinerated ash particles maintain a small particle size without being agglomerated and fused, and are sent to the post-combustion grate 5c. The reaction efficiency for the detoxification process by the reaction with the carbon dioxide in the circulating exhaust gas on the post-combustion grate 5c is increased.

  In the present invention, the oxygen concentration of the mixed gas with respect to the dry grate 5a and the combustion grate 5b is made lower than the conventional one, but the flow rate is higher than when supplying conventional air, and the total amount of oxygen supplied into the combustion chamber 2 is increased. Will supply the amount of oxygen required for the combustion of waste without changing the conventional method. As a result, the combustion of the waste can be performed stably, and the waste is completely burned.

  For the generation of the mixed gas, a part of the exhaust gas discharged from the bag filter 11 is extracted and used as a circulating exhaust gas. The oxygen concentration of the circulating exhaust gas is 2 to 5 vol%, and the circulating exhaust gas and air are mixed and supplied to each grate 5a, 5b, 5c as a mixed gas.

  The oxygen concentration and supply flow rate of the mixed gas are controlled to the desired oxygen concentration and supply flow rate by controlling the circulation exhaust gas supply flow rate and the air supply flow rate.

  In this embodiment, it is preferable to adjust the oxygen concentration of the mixed gas supplied to the lower part of the dry grate 5a and the combustion grate 5b to 14-18 vol% by an oxygen concentration adjusting means. The reason is that if the lower limit is less than 14 vol%, the combustion of waste is not stable, and the amount of CO and soot increases, which is not suitable. If the upper limit is higher than 18 vol%, it is not suitable on the grate. It is not possible to suppress an excessively high temperature atmosphere when the waste is combusted, agglomeration and fusion of the incinerated ash particles occurs, and the presence ratio of the large-sized incinerated ash particles increases, and the post-combustion grate 5c This is because the efficiency of detoxification of incinerated ash is low, so it becomes unsuitable.

  Moreover, it is preferable to adjust the oxygen concentration of the mixed gas supplied below the post-combustion grate 5c to 2 to 14 vol% by the oxygen concentration adjusting means. The reason is that if it is less than 2 vol% of the lower limit, soot combustion cannot be performed sufficiently, and it is unsuitable. If it is higher than 14 vol% of the upper limit, the reaction efficiency of carbon dioxide and incinerated ash becomes low and unsuitable.

  Furthermore, the preferable range of the particle size of the incinerated ash particles generated by burning the waste on the combustion grate 5b is preferably such that the particle size of the incinerated ash particles of 80% or more of the total weight of the incinerated ash is 5 mm or less. The oxygen concentration of the mixed gas supplied to the combustion grate 5b is adjusted by the oxygen concentration adjusting means so as to be in the particle size range of the incinerated ash particles.

  Such an incinerator of this embodiment is operated in the following manner.

  First, when the waste W is thrown into the waste inlet 3, the waste W is deposited on the dry grate 5 a, and on the combustion grate 5 b and the post-combustion grate 5 c by the operation of each grate 5 a, 5 b, 5 c. Moving upward, a waste layer is formed on each grate 5a, 5b, 5c.

  The drying grate 5a and the combustion grate 5b receive the mixed gas of the circulating exhaust gas and air as a drying gas and a combustion gas through the wind box, respectively, whereby the waste on the drying grate 5a and the combustion grate 5b is dried. And then burned. In the post-combustion grate 5c, the mixed gas of the circulating exhaust gas and air is received as the post-combustion gas and the incineration ash detoxification treatment gas through the wind box, and the post-combustion and incineration ash detoxification processing is performed.

  The unburned gas generated in the combustion chamber 2 is guided to the secondary combustion chamber 4 where it is mixed and stirred with the secondary air for secondary combustion, and the combustion exhaust gas from the secondary combustion chamber 4 is discharged from the waste heat boiler 10. Heat recovered. After the heat is recovered, the combustion exhaust gas discharged from the waste heat boiler 10 is sent to the bag filter 11 for dust removal. The combustion exhaust gas after being detoxified by the bag filter 11 is discharged from the chimney 12 into the atmosphere.

  In the dry grate 5a, the waste W is mainly dried and ignited. That is, drying is performed in the upstream region in the flow direction of the waste W of the dry grate 5a, and ignition (combustion start) is performed in the downstream region. Accordingly, drying and ignition of the waste W on the dry grate 5a requires heat for heating but not so much oxygen. Under such circumstances, the mixed gas of circulating exhaust gas and air adjusted to an oxygen concentration of 14-18 vol% fed from the wind box is suitable as the drying and ignition gas for the above-mentioned drying and ignition. .

  Next, the combustion grate 5b receives a mixed gas of circulating exhaust gas and air in which the oxygen concentration blown from the bottom of the combustion grate 5b is adjusted to 14 to 18 vol%, and mainly performs thermal decomposition and partial oxidation of the waste W. Combustible gas is generated and combustible gas and solid matter are combusted. Combustion of the waste W is substantially completed in the combustion grate 5b. In this combustion, the oxygen concentration of the mixed gas is adjusted to a concentration lower than that of air, so that the temperature atmosphere is prevented from becoming excessively high, and the incinerated ash particles are agglomerated and fused to become large particle size particles. Incineration ash can maintain a small particle size.

  After that, on the post-combustion grate 5c, the waste W is slightly left in response to the mixed gas of the circulating exhaust gas and the air whose oxygen concentration blown from below the post-combustion grate 5c is adjusted to 2 to 14 vol%. Incineration ash is made harmless while unburned parts such as fixed carbon are completely burned. The incinerated ash after detoxification is discharged from the ash discharge unit 6.

  The detoxification treatment of the incineration ash on the post-combustion grate 5c is caused by reacting carbon dioxide contained in the circulating exhaust gas with lead contained in the incineration ash to form a carbonate and make it hardly soluble. This is done by suppressing lead elution. At that time, carbon dioxide contained in the circulating exhaust gas reacts with calcium oxide contained in the incinerated ash to become calcium carbonate, so that the incinerated ash has a poor solubility in which the pH is lowered and lead is hardly soluble. It becomes a region, and the elution of lead from the incinerated ash is further suppressed.

  On the combustion grate 5b, the incinerated ash is not agglomerated and fused and maintains a small particle size, so that the contact efficiency between the incinerated ash particles and carbon dioxide on the post-combustion grate 5c is high, and it is detoxified. Efficiency can be increased. Thus, since the detoxification process of the incinerated ash on the post-combustion grate 5c proceeds sufficiently, it is not necessary to perform another detoxification process after discharging the incinerated ash, and the processing cost can be reduced.

  In the incinerator of the present embodiment, incineration ash layer temperature control means for controlling the temperature of the incineration ash layer on the post-combustion grate in the range of 400 to 700 ° C. is provided, and the incineration ash layer temperature control means is the post-combustion grate. It is also possible to control at least one of the primary air supply amount and the circulating exhaust gas supply amount supplied downward. By controlling the temperature of the incinerated ash layer on the post-combustion grate within the range of 400 to 700 ° C, calcium oxide or calcium hydroxide contained in the incinerated ash reacts with carbon dioxide in the circulating exhaust gas to produce calcium carbonate. It is possible to accelerate the reaction to make the incinerated ash have a low pH hardly soluble region where lead is hardly soluble. More preferably, the temperature of the incinerated ash layer is in the range of 600 to 700 ° C. If the temperature of the incinerated ash layer is less than 400 ° C, the above reaction does not occur, and if it is higher than 700 ° C, a reverse reaction occurs in which the generated calcium carbonate is decomposed.

  Know the correlation between the temperature of the post-combustion grate and the temperature of the incinerated ash layer on the post-combustion grate in advance, measure the temperature of the post-combustion grate, and determine the temperature of the incinerated ash layer on the post-combustion grate. It is preferable to control at least one of the primary air supply amount and the circulating exhaust gas supply amount supplied below the post-combustion grate based on the obtained and calculated temperature of the incinerated ash layer. The primary air supply amount supplied below the post-combustion grate is adjusted by adjusting the opening of the damper or valve 9c of the primary air supply means II, and the circulating exhaust gas supply amount is circulated by the blower 15 of the circulating exhaust gas supply means IV. It is adjusted by adjusting the amount of exhaust gas supplied and the opening of the damper or valve 14c.

  Waste is incinerated using the waste incinerator shown in Fig. 1, and the incineration ash discharged from the incinerator is subjected to a lead elution test based on the environmental standards test method related to soil contamination of Ministry of the Environment Notification No. 46 soil. Solution pH and elution lead concentration were measured. Moreover, the average particle diameter of the incinerated ash particles was measured. Next, a comparative example and an example show the results together with the supply status of primary air, the average particle size of the obtained incinerated ash, the eluate pH of the incinerated ash, and the lead elution concentration.

<Comparative example>
Supply air to dry grate, combustion grate, post-combustion grate 7mm average particle size of incinerated ash
Eluent pH 12.5
Lead elution concentration 1.6mg / l

<Example>
Supplying mixed gas of circulating exhaust gas and air to dry grate, combustion grate and post-combustion grate
Eluate pH 11.5
Lead elution concentration less than 0.01mg / l

  As can be seen from these results, in the examples, the incinerated ash could be less than 0.01 mg / l, which is a lead elution standard that can be used as civil engineering materials such as landfill roadbed materials. In the comparative example, the elution standard was exceeded.

DESCRIPTION OF SYMBOLS 1 Incinerator 2 Combustion chamber 5a Dry grate 5b Combustion grate 5c Post combustion grate
II Primary air supply means
IV Circulating exhaust gas supply means

Claims (14)

A combustion chamber of an incinerator that burns waste is provided with a dry grate, a combustion grate, and a post-combustion grate, and is provided with primary air supply means for supplying primary air below each grate. In the lattice-type waste incinerator,
Circulating exhaust gas supply means for supplying a part of the exhaust gas from the incinerator to the lower side of the dry grate, the combustion grate and the post-combustion grate, and mixing of the primary air and the circulating exhaust gas supplied to the lower side of the respective grate A grate-type waste incinerator having oxygen concentration adjusting means for adjusting the oxygen concentration of gas.   The oxygen concentration adjusting means adjusts the oxygen concentration of the mixed gas supplied below the dry grate and the combustion grate to 14 to 18 vol%, and the oxygen concentration of the mixed gas supplied below the post-combustion grate to 2 to 14 vol%. The grate-type waste incinerator according to claim 1, which is adjusted respectively.   Incineration ash layer temperature control means for controlling the temperature of the incineration ash layer on the post-combustion grate to a predetermined temperature, and the incineration ash layer temperature control means includes the primary air supply amount and the circulation supplied below the post-combustion grate The grate-type waste incinerator according to claim 1 or 2, wherein at least one of the exhaust gas supply amounts is controlled.   The grate-type waste incinerator according to claim 3, wherein the incineration ash layer temperature control means controls the temperature of the incineration ash layer on the post-combustion grate within a range of 400 to 700 ° C. In a waste incineration method for supplying primary air below a dry grate, a combustion grate and a post-combustion grate provided in a combustion chamber of an incinerator for burning waste,
A part of the exhaust gas from the incinerator is supplied below the dry grate, combustion grate and post-combustion grate, and the oxygen concentration in the mixed gas of primary air and circulating exhaust gas supplied below each grate Waste incineration method characterized by adjusting   The oxygen concentration of the mixed gas supplied below the dry grate and the combustion grate is adjusted to 14-18 vol%, and the oxygen concentration of the mixed gas supplied below the post-combustion grate is adjusted to 2-14 vol%, respectively. The waste incineration method according to claim 5.   The grate-type waste incineration method according to claim 5 or 6, wherein the temperature of the incinerated ash layer on the post-combustion grate is controlled in a range of 400 to 700 ° C. A combustion chamber of an incinerator that burns waste is provided with a dry grate, a combustion grate, and a post-combustion grate, and is provided with primary air supply means for supplying primary air below each grate. A device for treating incineration ash generated by burning waste in a grid-type waste incinerator,
Circulating exhaust gas supply means for supplying a part of the exhaust gas from the incinerator to the lower side of the dry grate, the combustion grate and the post-combustion grate, and mixing of the primary air and the circulating exhaust gas supplied to the lower side of the respective grate An incineration ash treatment apparatus comprising oxygen concentration adjusting means for adjusting the oxygen concentration of gas.   The oxygen concentration adjusting means adjusts the oxygen concentration of the mixed gas supplied below the dry grate and the combustion grate to 14 to 18 vol%, and the oxygen concentration of the mixed gas supplied below the post-combustion grate to 2 to 14 vol%. The incineration ash treatment apparatus according to claim 8, which is adjusted respectively.   Incineration ash layer temperature control means for controlling the temperature of the incineration ash layer on the post-combustion grate to a predetermined temperature, and the incineration ash layer temperature control means includes the primary air supply amount and the circulation supplied below the post-combustion grate The incineration ash treatment apparatus according to claim 8 or 9, wherein at least one of the exhaust gas supply amounts is controlled.   The incineration ash treatment apparatus according to claim 10, wherein the incineration ash layer temperature control means controls the temperature of the incineration ash layer on the post-combustion grate within a range of 400 to 700 ° C. A grate-type waste incinerator provided with primary air supply means for supplying primary air to a lower part of a dry grate, a combustion grate and a post-combustion grate provided in a combustion chamber of an incinerator for burning waste A method for treating incinerated ash generated by burning waste using
A part of the exhaust gas from the incinerator is supplied below the dry grate, combustion grate and post-combustion grate, and the oxygen concentration in the mixed gas of primary air and circulating exhaust gas supplied below each grate A method for treating incinerated ash, characterized in that the method is adjusted.   The oxygen concentration of the mixed gas supplied below the dry grate and the combustion grate is adjusted to 14-18 vol%, and the oxygen concentration of the mixed gas supplied below the post-combustion grate is adjusted to 2-14 vol%, respectively. The incinerated ash treatment method according to claim 12.   The incinerated ash treatment method according to claim 12 or 13, wherein the temperature of the incinerated ash layer on the post-combustion grate is controlled in a range of 400 to 700 ° C.

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