JP2001065844A - Method and apparatus for spheroidizing incineration ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for spheroidizing incineration ash wherein the incineration ash is formed into a molten spheroid circulating fluidized incineration where incineration ash is produced. SOLUTION: A circulating fluidizing incinerator is adapted such that in a furnace structure 1 consisting of a riser section 2 that forms a main combustion chamber, a cyclone section 3 for separating fluid sand 5 in waste gas, and a downcomer section 4 that forms a lowering flow passage, a circulation flow passage is formed along which passage the fluidizing sand 5 is circulated. In the incinerator, fuel oil is injected from a gun burner 12 into a furnace top of the riser section 2 communicated with the cyclone section 3 and is gasified as a combustion medium for combustion. Hereby, a high temperature melting region is formed in an upper space of a main combustion chamber, and incineration ash rising along the riser section 2 together with the fluidizing sand 5 is melted and spheroidized during passage of the high temperature melting region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for incinerating sewage sludge in a fluidized incinerator and spheroidizing generated incineration ash, and more particularly to a method and an apparatus for spheroidizing incineration ash.

[0002]

2. Description of the Related Art Conventionally, a circulating fluidized-bed furnace for incinerating sewage sludge is, for example, as shown in FIG. In FIG. 2, a furnace body 1 includes a riser section 2 forming a main combustion chamber, a cyclone section 3, and a downcomer section 4 forming a descending flow path.
And constitutes a circulation channel through which the fluidized sand 5 circulates in the furnace body.

[0003] The riser section 2 forming the main combustion chamber has a plurality of dispersion pipes 6 provided at the bottom of the furnace. Above the dispersion pipes, an auxiliary burner 7, a secondary air port 8, a starter burner 9, and a cake feeder 10 are sequentially arranged. Is provided. The riser 2 communicates with the cyclone 3 at the furnace top. Cyclone part 3
The furnace top communicates with an exhaust gas treatment system (not shown),
The downcomer unit 4 communicating with the lower end of the cyclone unit 3
A sand circulation air diffuser 11 is provided at the lower end side.

At the start of furnace operation, the starting burner 9 is ignited, burned at a high air ratio with combustion air supplied together with fuel, the furnace temperature is raised to a predetermined temperature, and the temperature of the fluidized sand 5 is raised. Provide a predetermined heat capacity in the furnace. on the other hand,
After supplying air from a blower (not shown) and raising the temperature of the air through a heat exchanger (not shown), high-temperature air is supplied into the furnace by a dispersion pipe 6, and the air ejected from the dispersion pipe 6 receives and flows. The sand 5 flows and circulates in the furnace. This air becomes the main combustion air in which the sludge burns. Further, fuel oil is injected from the auxiliary burner 7 into the furnace by the carrier air, and the combustion of the fuel oil raises the sand layer temperature to keep the furnace temperature at about 850 ° C.

In this state, the dewatered cake such as sewage sludge introduced into the riser unit 2 from the cake injecting machine 10 is instantaneously dried, gasified and burned by the stirring action of the high-temperature fluidized sand 5. At this time, the sand layer temperature changes due to the change in the water content of the sludge. However, the fuel oil is injected into the furnace from the auxiliary combustion burner 7 by the carrier air, and the sand layer temperature is increased by burning the fuel oil. Control. The combustion gas generated by the drying, thermal decomposition and combustion of the sludge receives the secondary air supplied into the furnace from the secondary air port 8 and is completely burned. This low-air ratio two-stage combustion suppresses the generation of NOx.

The flue gas generated in the riser section 2 is guided to the cyclone section 3 from the top of the riser section 2 together with the fluidized sand 5 and incineration ash. In the cyclone unit 3, the fluidized sand 5 is separated from the exhaust gas, the collected fluidized sand 5 is guided to the downcomer unit 4, and the incinerated ash and the exhaust gas are taken out from the top and discharged to an exhaust gas treatment facility (not shown). The fluidized sand 5 that has fallen into the downcomer unit 4 receives air diffused from the sand circulation air diffuser 11 and is returned to the riser unit 2.

[0007]

However, in recent years, effective utilization of incinerated ash has been attempted due to lack of landfill sites. This method of use includes soil improvement materials, roadbed materials, tiles, permeable blocks, and the like. When incinerated ash is used, there is a method of forming a molten spheroid having a particle size (several tens of micrometers) in an incinerated ash spheroidizing furnace in order to prevent heavy metals from dissolving and improve water absorption.

In this incineration ash spheroidizing furnace, a spheroidizing burner is installed at the top of a cylindrical vertical furnace body, and the inside of the furnace is heated to a melting temperature or higher (about 1300 to 2000 ° C.) by a high temperature flame (1300 to 2000 ° C.). (1400 ° C.). In this state,
The incinerated ash is blown out into a high-temperature flame from an incinerated ash supply port arranged at the center of the burner nozzle, and the incinerated ash is heated and melted while passing through the flame, and spheroidized by its surface tension.

As described above, in order to make incinerated ash into a molten spheroidized product while keeping its very small diameter, it is necessary to form a high-temperature flame by a burner. In addition to a fluidized incinerator, a separate incinerated ash spheroidizing furnace is required. Need to be installed. For this reason, there has been a problem that the installation space increases and the cost increases. An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a method and an apparatus for spheroidizing incinerated ash that forms incinerated ash into a molten spheroidized product in circulating fluidized incineration in which incinerated ash is generated.

[0010]

According to a first aspect of the present invention, there is provided a method for spheroidizing incinerated ash, comprising: a riser section for forming a main combustion chamber; In a circulating fluidized incinerator in which a circulating flow path for circulating fluidized sand is formed inside a furnace body including a cyclone section 3 for separating water and a downcomer section 4 for forming a descending flow path, the furnace communicates with the cyclone section 3. Fuel oil is sprayed from the gun burner 12 into the furnace top of the riser unit 2, and the fuel oil is gasified and burned using the fluidized sand 5 as a combustion medium, thereby forming a high-temperature melting region in the upper space of the main combustion chamber, The incinerated ash that rises in the riser section 2 together with the sand 5 is melted and spheroidized while passing through the high-temperature melting region.

With the above-described structure, the fuel oil sprayed from the gun burner 12 instantaneously burns by expanding the contact area with the air in the furnace by using the high-temperature fluidized sand 5 as a combustion medium. For this reason, it is not necessary to separately supply combustion air into the furnace, and combustion at a low air ratio that suppresses generation of NOx can be maintained. The spherical ash spheroidized in the high-temperature melting region is introduced into the cyclone section 3 along with the flow of the exhaust gas along with the flowing sand, is separated from the flowing sand 5 in the cyclone section 3, and is discharged to the next system together with the exhaust gas.

According to the second aspect of the present invention, the spheroidizing apparatus for incinerated ash according to the present invention forms a riser section 2 forming a main combustion chamber, a cyclone section 3 separating fluidized sand 5 from exhaust gas, and a descending flow path. In the circulating fluidized-bed incinerator in which the furnace body 1 is constituted by the downcomer unit 4 and the circulating flow path in which the fluidized sand 5 circulates inside the furnace body 1, the furnace top of the riser unit 2 communicating with the cyclone unit 3 And a gun burner 12 for spraying fuel oil.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. Members that perform the same operations as those described above with reference to FIG. 2 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 1, a riser section 2 forming a main combustion chamber of a circulating fluidized furnace communicates with a cyclone section 3 at the furnace top, and a gun burner 12 for spraying fuel to the furnace top of the riser section 2 is provided. The gun burner 12
It has a structure in which fuel oil is injected into the furnace with a small amount of instrument air without accompanying combustion air.

With the above-described configuration, at the time of operation, a predetermined heat capacity is ensured in the furnace by the high-temperature fluidized sand 5, and the main combustion air jetted from the dispersion pipe 6 and the secondary air supplied from the secondary air port 8 are used. The fluidized sand 5 is circulated in the furnace.
In this state, the dewatered cake such as sewage sludge charged into the riser unit 2 from the cake charging machine 10 is dried, ignited, and burned by the stirring action of the high-temperature fluidized sand 5, and NOx is generated by two-stage combustion at a low air ratio. Suppress.

At the top of the furnace of the riser section 2, the gun burner 1
By spraying the fuel oil from 2 and gasifying and burning the fuel oil using the fluidized sand 5 as a combustion medium, a high-temperature melting region is formed in the upper space of the main combustion chamber. The combustion exhaust gas generated in the riser portion 2 passes through the high-temperature melting region at the furnace top of the riser portion 2 together with the fluidized sand 5 and incineration ash, and the incineration ash is melted and spheroidized while passing through the high-temperature melting region.

In the cyclone section 3, the fluidized sand 5 is separated from the exhaust gas, guided to the downcomer section 4, and the molten spheroidized incinerated ash and the exhaust gas are taken out from the top and discharged to an exhaust gas treatment facility (not shown). I do. The fluidized sand 5 that has fallen into the downcomer unit 4 is returned to the riser unit 2 by air diffused from the sand circulation air diffuser 11.

[0017]

As described above, according to the present invention, a conventional flame is formed by employing a circulating fluidized incinerator as an incinerator and using high-temperature fluidized sand circulating in the furnace as a combustion medium. A high-temperature melting zone can be easily formed in the upper part of the main combustion chamber under low air ratio combustion conditions by using a simple burner that simply sprays fuel without using a burner with a complicated structure. By melting and spheroidizing the incinerated ash in the high-temperature melting region, there is no need to separately install an incinerated ash spheroidizing furnace, so that space saving and cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a circulating fluidized incinerator according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional circulating fluidized incinerator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace body 2 Riser part 3 Cyclone part 4 Downcomer part 5 Fluid sand 6 Dispersion pipe 7 Burning burner 8 Secondary air port 9 Starter burner 10 Cake feeding machine 11 Diffusion pipe for sand circulation 12 Gun burner

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F23G 7/00 104 B09B 3/00 303L (72) Inventor Osamu Yokota Oshiki Shizitsu, Namiwa-ku, Osaka-shi, Osaka No. 2-47, Kubota Co., Ltd. (72) Tadashi Yano 2-6-1, Nishijima, Nishiyodogawa-ku, Osaka-shi, Osaka Prefecture F-term in Kubota Shin-Yodogawa Environmental Plant Center (reference) 3K061 AA11 AB03 AC03 CA04 DA12 DA18 DB18 DB20 NB03 NB16 NB20 NB21 4D004 AA02 AA36 BA02 CA28 CA29 CB01 CB34 CB42 CB43 CB44 4D059 AA03 BB01 BB13

Claims (2)

[Claims] 1. Fluid sand circulates inside a furnace body comprising a riser part forming a main combustion chamber, a cyclone part separating fluid sand from exhaust gas, and a downcomer part forming a descending flow path. In a circulating fluidized incinerator having a circulation flow path, spraying fuel oil from a gun burner into the furnace top of a riser unit communicating with a cyclone unit, and gasifying and burning the fuel oil using fluidized sand as a combustion medium,
A spheroidizing incineration ash characterized by forming a high-temperature melting zone in the upper space of the main combustion chamber and melting incineration ash that rises in the riser section together with fluidized sand while passing through the high-temperature melting zone Method. 2. A furnace body comprising a riser part forming a main combustion chamber, a cyclone part separating fluidized sand from exhaust gas, and a downcomer part forming a descending flow path. A spheroidizing apparatus for incinerated ash, wherein a gun burner for spraying fuel oil is provided on a furnace top of a riser section communicating with a cyclone section in a circulating fluidized incinerator having a circulation flow path through which sand circulates.