JP2022043107A - Sludge incineration device and sludge incineration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sludge incineration device and a sludge incineration method capable of enhancing heat delivery efficiency to a whole fluidized bed and contributing to stable combustion of objects to be incinerated while maintaining a high fluidized bed temperature.

SOLUTION: A sludge incineration device includes: a fluidized bed type incinerator 1; an incinerated object supply device 2 and an incinerated object supply part 16 which are sludge supply parts supplying sludge from an upper side of a fluidized bed of the fluidized bed type incinerator 1 into the fluidized bed type incinerator 1; and a fuel supply device 3 and a fuel supply part 17 which are supply parts supplying solidified fuel B obtained by integrally solidifying at least combustibles including waste plastic and sand from the upper side of the fluidized bed of the fluidized bed type incinerator 1 into the fluidized bed type incinerator 1.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

Conventionally, a fluidized bed incinerator has been widely used as an incinerator that efficiently burns incinerators that are combustibles such as sludge. This fluidized bed incinerator uses a combustion assisting material and blows fluidized / combustion air from the bottom of the fluidized bed through a nozzle to flow the sand layer constituting this fluidized bed, and the fluidized bed and sand. The incinerator is crushed and gasified by utilizing its excellent heat transfer characteristics, and a free board, which is a combustion chamber for burning the generated combustible gas, is formed in the space above the fluidized bed. In particular, when the water content of the incinerator is high, the incinerator does not self-combust by itself, so if the sand layer is sufficiently heated by burning a combustion aid such as natural gas or heavy oil in the sand layer, it will be incinerated. You can burn things.

By the way, it is a well-known fact that the treatment of waste plastic has become an issue in recent years, and a place where it can be effectively used is required. Therefore, Patent Document 1 proposes incinerating waste plastic and sludge in a mixed state in a fluidized bed type sludge incinerator. According to this Patent Document 1, waste plastic can be effectively used as an auxiliary fuel when incinerating sludge, and it contributes to the reduction of fossil fuels conventionally used as an auxiliary material in a fluidized bed type sludge incinerator. Therefore, it also has the advantage of reducing the cost of incinerating sludge as an incinerator.

Japanese Patent Application Laid-Open No. 11-182834

However, the waste plastic used in the technique disclosed in Patent Document 1 has a low density of itself, and even if it is simply mixed with sludge, the surface of the sand layer (upper surface of the layer) before the waste plastic falls into the sand layer. Since it burns quickly in the vicinity, the temperature of the freeboard part rises, but the heat applied to the entire sand layer is not good, which in turn causes the temperature of the sand layer to drop, which causes problems in sludge combustion. .. Further, when the waste plastic and the sludge are mixed before being put into the fluidized bed incinerator, there is a problem that the waste plastic gets entangled with the conveyor screw or the like in the sludge transport facility and causes clogging.

The present invention has been made in view of such circumstances, and is a sludge capable of increasing the thermal efficiency of the entire fluidized bed and contributing to stable combustion of the incinerator while maintaining the fluidized bed temperature at a high temperature. An object of the present invention is to provide an incinerator and a sludge incineration method.

The sludge incinerator according to the present invention includes a fluidized bed type incinerator, a sludge supply unit that supplies sludge into the incinerator from above the fluidized bed of the incinerator, and at least combustibles and sand containing waste plastic. It has a supply unit for supplying the solidified fuel integrally solidified into the incinerator from above the fluidized bed of the incinerator.

The sludge incinerator method according to the present invention is a sludge incinerator using a fluidized bed type incinerator, in which sludge is supplied into the incinerator from above the fluidized bed of the incinerator, and at least a combustible substance containing waste plastic is contained. The solidified fuel in which and sand are integrally solidified is supplied into the incinerator from above the fluidized bed of the incinerator.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a sludge incinerator and a sludge incinerator method capable of increasing the thermal efficiency to the entire fluidized bed and contributing to stable combustion of the incinerator while maintaining the fluidized bed temperature at a high temperature.

It is a block diagram which shows the fluidized bed type incinerator which incinerates the incinerator using the solidified fuel of this invention as an auxiliary material, and the related equipment. It is a graph which shows the experimental result of Example 1. FIG. It is a graph which shows the experimental result of Example 2.

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

FIG. 1 is a schematic configuration diagram showing a fluidized bed incinerator for incinerating an incinerator using the solidified fuel of the present invention as an auxiliary material and related equipment thereof.

In FIG. 1, reference numeral 1 is a fluidized layer incinerator (hereinafter referred to as “incinerator”) for incinerating an incinerator, and the incinerator 1 is a subject for supplying an incinerator A such as sludge to the incinerator 1. Air as a fluid gas forming a fluid layer C made of silica sand as fluid sand in the fuel supply device 3 and the incinerator 1 for supplying the solidified fuel B as an auxiliary fuel to the incinerator 2 and the incinerator 1. An air supply device 4 such as a blower to be supplied, an exhaust gas treatment device 5 for treating the exhaust gas E from the incinerator 1, and a heat exchanger 6 for heat-exchanges the air from the air supply device 4 with the exhaust gas E to raise the temperature are connected. ing. In this embodiment, silica sand is used as the flowing sand, but other sand may be used.

In the incinerator 1, an air-permeable bed 12 formed of an air-permeable material is provided at the bottom of a vertically long furnace body 11, and the lower part of the air-permeable bed 12 is formed as a wind box 13. The side wall of the air box 13 is provided with an air feeding unit 14 for feeding the air from the air supply device 4 into the air box 13 after the temperature is raised by the heat exchanger 6.

In the incinerator 1, the upper part of the air-permeable bed 12 is formed as a combustion space 15, and fluidized sand is charged into the combustion space 15, and air is supplied to the air box 13 from the air supply device 4. When the incinerator A and the solidified fuel B are put into the combustion space 15, a fluidized bed C is formed in the lower part of the combustion space 15 directly above the air permeable bed 12 by the flow of fluidized sand. A free board portion D is formed above the fluidized bed C.

In the middle portion in the height direction of the incinerator 1, an incinerator supply unit 16 for supplying the incinerator A from the incinerator supply device 2 into the furnace is provided at a position above the upper layer portion of the fluidized bed C. Similarly, a fuel supply unit 17 for supplying the solidified fuel B into the furnace is provided at a position above the upper layer of the fluidized bed C. Further, at the top of the incinerator 1, an exhaust gas exhaust unit 18 is provided to which a pipeline for introducing the exhaust gas E from the freeboard unit D into the heat exchanger 6 is connected.

The incinerator supply device 2 appropriately mixes sludge or other waste combustibles including sludge as the incinerator A of humid waste, and supplies the incinerator from the incinerator supply unit 16 into the furnace. It has become. The incinerator supply device 2 has an incinerator storage unit 2A that mixes and stores the incinerator A, and a feeder unit 2B that carries out the incinerator A and carries it out to the incinerator supply unit 16. ing. Here, sludge refers to humid waste that is incinerated in a fluidized bed incinerator, and is, for example, sludge discharged from sewage sludge discharged from a sewage treatment plant, sludge discharged by treatment of factory wastewater, or the like.

The fuel supply device 3 receives and stores the solidified fuel B from the fuel forming device 31 and the fuel forming device 31 that receives the supply of sand and combustibles containing waste plastic and pressurizes them to form the solidified fuel B. It has a fuel storage / carry-out device 32 that carries out a predetermined amount of the solidified fuel B and carries it out to the fuel supply unit 17 of the incinerator 1. The fuel storage / unloading device 32 has a tank-shaped fuel storage section 32A for storing the solidified fuel B and a feeder section 32B such as a screw feeder that cuts out a predetermined amount of the solidified fuel B and carries it out. 32B is connected to the fuel supply unit 17 via a pipeline.

The fuel forming apparatus 31 is supplied with sand as a raw material for the solidified fuel B, and is a waste plastic-containing combustible substance, that is, waste plastic and other combustible substances (for example, waste paper, waste fiber, waste tatami mat, etc.) or waste. It is configured to receive only the plastic, mix the combustibles containing waste plastic with sand while appropriately crushing them, pressurize this mixture, and compress-mold it into a lump of appropriate size to obtain solidified fuel B. There is. Here, the sand used for the solidified fuel B may be silica sand, iron-containing granules, or the like, in addition to general sand. In the present embodiment, the sand used for the solidified fuel B is silica sand, that is, sand of the same quality as liquid sand. The fuel forming apparatus 31 may be installed on the machine side of the incinerator 1 so that the solidified fuel B is supplied to the incinerator 1 from the fuel storage / carrying out apparatus 32 connected to the fuel forming apparatus 31. However, the fuel forming apparatus 31 may be installed on a site different from the incinerator 1, and the solidified fuel B produced may be transported and supplied to the site where the incinerator 1 is installed.

Next, a procedure for producing a solidified fuel using the apparatus of the present embodiment shown in FIG. 1 and a procedure for incinerating an incinerator using this solidified fuel as a combustion improver will be described.

First, sludge or sludge as incinerator A and other waste are supplied to the incinerator 1 from the incinerator supply unit 16 in a state of being mixed by the incinerator supply device 2. Since the incinerator A such as sludge contains combustibles, it burns when sufficiently heated from the outside.

On the other hand, combustibles containing sand and waste plastic are charged into the fuel molding device 31 of the fuel supply device 3. The combustibles containing waste plastic may be only waste plastic. The waste plastic-containing combustible material is appropriately crushed in the fuel molding apparatus 31 and mixed with sand to form a mixture, and the mixture is pressurized and compression-molded into granules of an appropriate size to solidify the fuel B. Will form. Since this solidified fuel B is solidified integrally with sand, it has a large specific gravity and easily descends into the fluidized bed C in the furnace. The solidified fuel B is stored in the fuel storage section 32A of the fuel storage / delivery device 32 of the fuel supply device 3, and then an appropriate amount is cut out by the feeder section 32B and carried out, and the solidified fuel B is taken out from the fuel supply section 17 as an auxiliary fuel in the furnace. Is supplied to. Then, in the incinerator 1, the air sent into the air box 13 permeates the air-permeable bed 12 and rises, and the incinerated material A and the solidified fuel B on the air-permeable bed 12 flow. It flows in the fluidized bed C made of sand.

Since the incinerator A contains combustibles, once ignited in the incinerator 1, it can be continuously burned, but if the incinerator A contains a large amount of water, it is combustible. Is low. Therefore, in order to burn the incinerator A, the solidified fuel B as a combustion auxiliary material is used to promote the combustion. In the present embodiment, the solidified fuel B is formed into a grain mass by pressurizing sand and a combustible substance containing waste plastic, and has a large specific gravity, so that the solidified fuel B quickly drops without burning out on the surface of the fluidized bed C. It reaches the inside of the fluidized bed C. Therefore, this solidified fuel B burns in the entire fluidized bed C and heats the fluidized sand in the entire fluidized bed C to increase the thermal efficiency to the fluidized sand. As a result, the incinerator A is heated by the fluidized sand and burns inside the fluidized layer C, and at the same time, combustible gas and ash as unburnable matter are generated, and the combustible gas is burned by the free board portion D and is a high-temperature exhaust gas. E is generated and exhausted from the exhaust gas exhaust unit 18, and the ash content is discharged to the outside of the furnace from the discharge port (not shown) at the bottom of the furnace and is appropriately disposed of. Further, when the waste plastic-containing combustible material of the solidified fuel B is burned in the fluidized bed C, the sand constituting the solidified fuel B remains. In the present embodiment, the sand that is mixed with the waste plastic-containing combustible material to form the solidified fuel B is silica sand as described above. That is, the sand remaining after the combustion of the combustible waste containing waste plastic is silica sand, which is the same as the silica sand which is the fluidized sand forming the fluidized bed C, and even if it remains as the fluidized sand in the fluidized bed C, it flows. It does not impair the function of the layer.

The high-temperature exhaust gas E is brought to the heat exchanger 6, the air is raised by heat exchange with the air from the air supply device 4, the exhaust gas E itself is lowered in temperature, detoxified by the exhaust gas treatment device 5, and then the atmosphere. Is released to.

The air whose temperature has risen due to heat exchange with the exhaust gas E in the heat exchanger 6 is sent from the air feeding unit 14 to the air box 13, and then the air permeates through the air permeation bed 12 and rises from the air permeation bed 12. In the upper combustion space 15, it contributes to the formation of the fluidized bed C by the fluidized sand and also contributes to the combustion of the combustible gas in the free board portion D.

In the present embodiment, the sand used for the solidified fuel B is silica sand, which is the same quality as the fluidized sand, but it is not essential that the sand is the same as the fluidized sand. For example, when sand having a specific gravity higher than that of the fluidized sand is used for the solidified fuel B, the sand does not stay in the furnace as the fluidized sand after the solidified fuel B burns in the fluidized layer C. Together with the ash, it will be discharged to the outside of the furnace from the discharge port at the bottom of the furnace.

Further, the present invention is not limited to the application to the fluidized bed incinerator shown in FIG. 1, and the circulating fluidized bed having a circulation path to the furnace at the outlet of the incinerator and the fluidized sand captured by the cyclone. It can also be applied to a type incinerator.

Hereinafter, an embodiment in the case where the sand contained in the solidified fuel is silica sand will be referred to as “Example 1”, and an embodiment in the case where the sand contained in the solidified fuel is iron-making dust as iron-containing granules. This will be described as “Example 2”.

<Example 1>
An experiment was conducted in which sludge and solidified fuel were co-firing in a fluidized bed incinerator under the following setting conditions.
(1) Operating conditions-Fluidized bed dimensions: diameter 500 mm (inner diameter of the main body of the fluidized bed incinerator)
・ Flowing sand: Silica No. 5.5 ・ Gas superficial velocity: 0.3m / s (air injection velocity to the bottom of the furnace body)
-Incinerator: sludge and solidified fuel (sludge is dehydrated sewage sludge)
・ Sludge calorific value (low calorific value): 5MJ / kg
-The calorific value of the solidified fuel (low calorific value): 32 MJ / kg
-Composition of solidified fuel: plastic and silica sand (plastic is a mixture of various plastics such as polyethylene, polypropylene, PET, etc., silica sand is the same as fluid sand, and the mixing ratio of silica sand is shown in Table 1. Yes)
-Shape of solidified fuel: Cylindrical molded product (outer diameter is 20 mm or 30 mm, length is 30 to 60 mm)

(2) Operation method and evaluation method-Sludge and solidified fuel were poured from the top of the furnace body toward the fluidized bed.
-The amount of sludge input per hour was made the same for each condition for solidified fuel of various outer diameters and lengths.
-For solidified fuel, the supply rate was adjusted so that the amount of heat supplied per hour was equal. That is, since silica sand does not have a calorific value, the supply amount of the plastic part was kept constant.
-The amount of air supplied from the bottom of the furnace body to the bottom of the fluidized bed was also constant, and the air ratio was 1.35.
-Under the set conditions for each condition, the temperature of the sand layer of the fluidized bed rises over time due to the heat of combustion. Therefore, in order to control the temperature of the sand layer to a constant value (750 ° C.), water was continuously supplied into the sand layer for convenience. The amount of water supplied was defined as the "cooling water supply amount".
-The higher the thermal efficiency of the solidified fuel to be supplied to the sand layer, the greater the amount of cooling water supplied. Therefore, we decided to use the amount of cooling water supply as an index of thermal efficiency. That is, the amount of cooling water supplied under the condition that the sand mixing ratio of the solidified fuel was 0% was set to 1, and the amount of cooling water supplied under each condition was evaluated by a relative value (relative value of thermal efficiency).

砂混合比率（重量％）＝（固形化燃料中の砂重量）／（固形化燃料中の砂重量＋固形化燃料中のプラスチック重量） (3) Experimental results

Sand mixing ratio (% by weight) = (weight of sand in solidified fuel) / (weight of sand in solidified fuel + weight of plastic in solidified fuel)

The results in Table 1 are as shown in FIG. From Table 1 and FIG. 2, the following can be seen.
-As a result of the experiment, the thermal efficiency increased in the range of 5% by weight to 70% by weight of the sand mixing ratio as compared with the case where the sand mixing ratio was 0.
-In particular, the increase in thermal efficiency was remarkable in the range of 5% by weight to 60% by weight of the sand mixing ratio as compared with the case where the sand mixing ratio was 0.

Improving the thermal efficiency leads to a reduction in the amount of solidified fuel that must actually be supplied to the furnace, and has the effect of contributing to cost reduction and reduction of carbon dioxide emissions.

<Example 2>
An experiment was conducted in which sludge and solidified fuel were co-firing in a fluidized bed incinerator under the following setting conditions.
(1) Operating conditions-Fluidized bed dimensions: diameter 500 mm (inner diameter of the main body of the fluidized bed incinerator)
・ Flowing sand: Silica No. 5.5 ・ Gas superficial velocity: 0.3m / s (air injection velocity to the bottom of the furnace body)
-Incinerator: sludge and solidified fuel (sludge is dehydrated sewage sludge)
・ Sludge calorific value (low calorific value): 5MJ / kg
-The calorific value of the solidified fuel (low calorific value): 32 MJ / kg
-Composition of solidified fuel: plastic and iron-making dust (plastic is a mixture of various plastics such as polyethylene, polypropylene, PET, etc., and iron-making dust is mainly composed of iron and has a particle size of 0.2 to 0.5 mm. , The mixing ratio of ironmaking dust is shown in Table 2)
-Shape of solidified fuel: Cylindrical molded product (outer diameter is 30 mm, length is 30 to 60 mm)

(2) Operation method and evaluation method The same as in Example 1 was applied.

製鉄ダスト混合比率（重量％）＝（固形化燃料中の製鉄ダスト重量）／（固形化燃料中の製鉄ダスト重量＋固形化燃料中のプラスチック重量） (3) Experimental results

Iron-making dust mixing ratio (% by weight) = (Weight of iron-making dust in solidified fuel) / (Weight of iron-making dust in solidified fuel + Weight of plastic in solidified fuel)

The results in Table 2 are as shown in FIG. From Table 2 and FIG. 3, the following can be seen.
-As a result of the experiment, the thermal efficiency increased in the range of 5% by weight to 70% by weight of the iron-making dust mixing ratio as compared with the case where the iron-making dust mixing ratio was 0.
-In particular, the increase in thermal efficiency was remarkable in the range of 5% by weight to 60% by weight of the iron-making dust mixing ratio as compared with the case where the iron-making dust mixing ratio was 0.

Improving the thermal efficiency leads to a reduction in the amount of solidified fuel that must actually be supplied to the furnace, and has the effect of contributing to cost reduction and reduction of carbon dioxide emissions.

1 Fluidized bed incinerator A Incinerator B Solidified fuel

Claims (2)

A fluidized bed incinerator and
A sludge supply unit that supplies sludge into the incinerator from above the fluidized bed of the incinerator, and
A supply unit that supplies solidified fuel, which is a solidified product of at least combustibles containing waste plastic and sand, into the incinerator from above the fluidized bed of the incinerator.
Sludge incinerator with. It is a sludge incinerator using a fluidized bed incinerator.
Sludge is supplied into the incinerator from above the fluidized bed of the incinerator.
A solidified fuel obtained by integrally solidifying at least combustibles containing waste plastic and sand is supplied into the incinerator from above the fluidized bed of the incinerator.
Sludge incinerator method.

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