JP2006297331A - Production method and apparatus of granulation particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the production method of granulation particles for sealing toxic heavy metals contained in refuse derived fuel in spherical solidified particles to perform detoxification. <P>SOLUTION: This production method of granulation particles comprises processes for: granulating fly ash into particles with particle sizes within a given range by an ash granulator 1; firing the refuse derived fuel containing granulation particles produced in the granulation process and toxic heavy metals by introducing it into a kiln 3, at 1,050-1,200°C; and post-firing by introducing combustion exhaust gas discharged from the firing process, granulation particles and refuse combustion ash into a downstream post-combustion furnace 5, melting refuse combustion ash attached to surfaces of the particles in the former stage of the post-combustion furnace 5 at 1,300-1,500°C, introducing cooling air in the latter stage of the post-combustion furnace 5 to cool granulation particles including particles in which the refuse combustion ash is present in a molten state on the surfaces, and forming substantially spherical solid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and apparatus for producing granulated particles, and more particularly to a method and apparatus for producing granulated particles that can be used for earth and sand substitutes, concrete aggregates, and the like.

  Conventionally, Patent Document 1 proposes a melting furnace for producing spherical powder slag from sludge incineration ash. FIG. 4 shows a spherical powder slag manufacturing process flow described in Patent Document 1. The conventional manufacturing method will be described with reference to FIG. 4. Reference numeral 50 represents sewage sludge incineration ash discharged from a sewage sludge incineration facility. The hopper 51 to be stored is a quantitative feeder, and the incinerated ash in the hopper 50 is cut out by the quantitative feeder 51 and then transported to a melting furnace 53 for producing spherical powder slag through a pipe 52 by a blower (not shown).

  As shown in FIG. 5, the melting furnace 53 gradually increases in size as the cross-sectional area in the furnace goes downward, and nozzles 55 as cooling air supply means are provided in the circumferential direction on each step portion 54 on the inner wall of the furnace. Several tens of them are attached to each other, and cooling air is jetted downward to lower the temperature of the furnace wall, thereby preventing the clinker from adhering to the furnace wall.

  A burner 56 is attached to the top of the melting furnace 53, and the burner 56 has a triple pipe structure including an incineration ash supply pipe, a fuel supply path, and a combustion gas supply path. During the high-temperature combustion flame S formed by the fuel and the combustion gas supplied from the fuel supply path and the combustion gas supply path, the incineration ash is brought together with a part of the combustion gas (air) from the incineration ash supply pipe. It is supplied and heated in the combustion flame S, and the incineration ash melts and spheroidizes in a floating state. The spheroidized molten particles are eventually carried out of the combustion flame S, and are rapidly cooled in a furnace maintained at a melting temperature or lower with cooling air from the nozzle 55 to solidify into spherical powder slag.

  Of the spherical powder slag, the spherical powder slag having a large particle size falls to the bottom of the furnace and is taken out from the outlet 57, while the spherical powder slag having a small particle diameter passes through the heat exchanger 59 together with the exhaust gas from the exhaust gas outlet 58. To the electric dust collector 60 and separated from the exhaust gas. Thereby, spherical powder slag is obtained from the spherical powder slag discharge port 57 and the electrostatic precipitator 60 provided in the hearth.

The melting furnace used in the above-described technique is to melt and spheroidize powder in a flame and is called a flame melting furnace. A similar flame melting furnace is also disclosed in Non-Patent Document 1. Has been.
Japanese Patent Laid-Open No. 11-337042 Journal of Sewerage Association Vol. 36 No.444 1999/10 “Technology for manufacturing molten powder by spheroidization of sewage sludge incineration ash”

  In recent years, in the promotion of energy power generation, circulating fluidized bed boilers that enable high-efficiency power generation from waste combustion, which is the core of the waste power generation field, have attracted attention.

In the problem of the prior art, in such a circulating fluidized bed boiler, in the flame melting method, the main fuel is oil and solid waste cannot be used as fuel. Therefore, there is a drawback that the operating cost is high and cannot contribute to CO ₂ emission reduction.

  Methods such as the plasma melting method and the induction heating method consume a large amount of electric power, and thus are not economical because of high operating costs.

  Conventionally, rotary kilns for ash firing have been used to produce artificial lightweight aggregates from sewage sludge combustion ash, but all fuel is fossil fuel.

  The present inventor has attempted to develop a technology that uses waste as a fuel for a rotary kiln for ash firing, and has found the following problems.

  That is, in the conventional calcination method using an ash firing rotary kiln, the waste combustion ash using waste fuel becomes fine fly ash of 10 to 40 microns and is accompanied by the combustion gas produced by the ash firing rotary kiln. Pass through a rotary kiln for firing. For this reason, waste combustion ash is not fully baked. If the waste combustion ash containing toxic heavy metals is not burned sufficiently, the toxic heavy metals will be contained in the waste combustion ash. After the combustion ash is discharged and collected, it is rendered harmless by adding chemicals. There is a problem that the processing cost becomes high.

  Further, there is a problem that the quality of the product cannot be ensured because the waste combustion ash adheres to the granulated particles granulated by the rotary kiln for ash firing, and the concentration of harmful heavy metals in the granulated product itself increases.

  Then, this invention makes it a subject to provide the manufacturing method and manufacturing apparatus of the granulated particle which can contain the harmful heavy metal contained in waste fuel in a spherical solidification particle, and can make it harmless.

  Other problems of the present invention will become apparent from the following description.

  The above-described problems of the present invention are solved by the following inventions.

(Claim 1)
A granulation step of granulating fly ash into particles having a predetermined range of particle sizes by an ash granulator;
A firing step of introducing waste fuel containing granulated particles and harmful heavy metals granulated in the granulation step into a kiln firing furnace and firing at a firing temperature of 1050 to 1200 ° C;
Combustion exhaust gas, granulated particles and waste combustion ash discharged from the firing step are introduced into a downstream post-combustion furnace, and adhere to the surface of the granulated particles at a temperature of 1300 to 1500 ° C. at the front stage of the post-combustion furnace. The waste combustion ash is melted, cooling air is introduced at a later stage of the post-combustion furnace, and the granulated particles including the granulated particles in which the waste combustion ash exists in a molten state are cooled on the surface. And a post-combustion step for producing a substantially spherical solidified product.

(Claim 2)
10 to 50 micron fly ash collected after combustion in a circulating fluidized bed boiler in which the granulation step generates high-temperature and high-pressure steam by combustion heat obtained by burning fuel selected from biomass, various industrial wastes and fossil fuels 2. The method for producing granulated particles according to claim 1, wherein a raw material comprising water, water and cement is agitated and kneaded and granulated into particles of a predetermined size.

(Claim 3)
The method for producing granulated particles according to claim 1 or 2, wherein the waste fuel containing the toxic heavy metal used in the firing step is waste such as waste plastic, PRF, and building waste.

(Claim 4)
The said baking process hold | maintains the granulated material granulated by the said granulation process at the baking temperature of 1050-1200 degreeC for 0.5 to 2 hours, and baked. A method for producing granulated particles.

(Claim 5)
The method for producing granulated particles according to any one of claims 1 to 4, wherein a combustion air ratio at the exit of the kiln firing furnace is 1.0 or more.

(Claim 6)
The method for producing granulated particles according to any one of claims 1 to 5, wherein the theoretical air ratio after fossil fuel is blown at the entrance of the post-combustion furnace is maintained at 0.9 to 1.1.

(Claim 7)
A granulator for granulating fly ash into particles having a predetermined particle size;
A kiln firing furnace for introducing waste containing granulated particles and harmful heavy metals granulated by the granulator and firing at a firing temperature of 1050 to 1200 ° C .;
The combustion exhaust gas, granulated particles, and waste combustion ash, which are disposed downstream of the kiln calcining furnace and discharged from the kiln calcining furnace, are introduced and adhered to the surface of the granulated particles at a temperature of 1300 to 1500 ° C. in the previous stage. The waste combustion ash is melted, cooling air is introduced at a later stage, and the granulated particles including the granulated particles in which the waste combustion ash exists in a molten state are cooled on the surface to form a substantially spherical shape. An apparatus for producing granulated particles, comprising a post-combustion furnace for producing a solidified product.

(Claim 8)
The apparatus for producing granulated particles according to claim 7, wherein the post-combustion furnace is a flame melting furnace.

  According to the first aspect of the present invention, it is possible to contain harmful heavy metals contained in the waste fuel in the spherical solidified particles and render them harmless. Further, the obtained granulated particles can be used as a silica sand substitute for a circulating fluidized bed boiler, a soil substitute such as a soil improvement material, and a concrete aggregate. The amount of toxic heavy metal elution contained in the manufactured granulated baked product satisfies the soil environment standard value, and the soil environment standard value is also satisfied for the elution of toxic heavy metal in the collected ash by the bag filter. Yes.

  According to invention of Claim 2, the fly ash generated from a circulating fluidized bed boiler can be used effectively.

  According to invention of Claim 3, a fuel unit price can be reduced to 1/5-1/10 compared with a fossil fuel.

  According to the fourth aspect of the present invention, it is possible to contain harmful heavy metals in the particles to render them harmless and to produce a solidified product.

  According to the fifth aspect of the present invention, the complete combustion of the waste fuel can be achieved in the kiln firing furnace.

  According to the sixth aspect of the present invention, it is possible to increase the flame temperature in the post-combustion furnace.

  According to the seventh and eighth aspects of the invention, it is possible to make the harmful heavy metal contained in the waste fuel contained in the spherical solidified particles harmless. Further, the obtained granulated particles can be used as a silica sand substitute for a circulating fluidized bed boiler, a soil substitute such as a soil improvement material, and a concrete aggregate. The amount of toxic heavy metal elution contained in the manufactured granulated baked product satisfies the soil environment standard value, and the soil environment standard value is also satisfied for the elution of toxic heavy metal in the collected ash by the bag filter. Yes.

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

  FIG. 1 is a flowchart showing a preferred embodiment of an apparatus for carrying out the method for producing granulated particles of the present invention. In the figure, 1 is an ash granulator, for example, a mixed stirring granulator, a bread granulator You can use the machine.

  This Embodiment demonstrates the example which employ | adopted the stirring granulator provided with the granulation tank 100 and the stirrer 101. FIG.

  After introducing fly ash (fly ash) into the granulation tank 100 and adding about 10% of water to the fly ash, the stirrer 101 is operated and agitation is performed to obtain granulated particles having a particle size in a predetermined range. . If necessary, a binder can also be used. The rotational speed of the stirrer 101 is preferably about 60 to 120 rpm for obtaining granulated particles having a particle size in a predetermined range.

  Although it does not specifically limit as fly ash introduced into the granulation tank 100, For example, the combustion ash (bug ash) etc. which are discharged | emitted from the circulating fluidized bed boiler which is not illustrated are mentioned, The particle size of fly ash is 10-50 normally. It is in the range of microns (average 20-40 microns). The circulating fluidized bed boiler generates high-temperature and high-pressure steam by combustion heat obtained by burning fuel selected from biomass, various industrial wastes, and fossil fuels.

  The particle size of the resulting granulated particles varies depending on the purpose of the product, such as 100 to 500 microns if the product obtained by the present invention is an earth and sand substitute, and 5 to 20 mm if the concrete aggregate (sand, pebbles, etc.). It is preferable to make it.

  It is preferable to allow natural curing in a building or the like for about 12 to 48 hours after granulation.

  The particles granulated by the agitation granulator 1 are conveyed to the kiln firing furnace 3 through the cutting unit 2, and the conveyance system will be described with reference to FIGS.

  As shown in FIG. 2, the particles granulated by the stirring granulator 1 are received by the hopper 102 and cut out by a predetermined amount by the screw feeder 201 through the input unit 200 of the cutting unit 2. The granulated particles that have been cut out are put into the charging unit 300 provided at the entrance of the kiln firing furnace 3 by the conveyor 202, and are introduced into the kiln firing furnace 3 by opening and closing the sealing rotary valve 301.

  The mode of the transport system may be the mode shown in FIG. That is, the cut-out part 2 is arranged in the vicinity of the entrance of the kiln firing furnace 3, the particles granulated by the stirring granulator 1 are received by the hopper 102, and the particles supplied from the hopper 102 are transferred to the cut-out part 2 by the conveyor 202. A predetermined amount is cut out by the screw feeder 201 through the charging unit 200. The granulated particles thus cut out are charged into a charging unit 300 provided at the entrance of the kiln firing furnace 3 and introduced into the kiln firing furnace 3 by opening and closing the sealing rotary valve 301.

  As the kiln firing furnace 3, for example, an internal combustion co-current firing rotary kiln having an activation burner can be used.

  As fuel for the kiln firing furnace 3, waste fuel containing toxic heavy metals is used. The waste fuel is cut out from the waste fuel cutout unit 4 by a predetermined amount. The waste fuel cutting unit 4 includes a charging unit 400 and a screw feeder 401.

  Examples of the waste fuel include waste plastics, RPF (Refuse Paper & Plastic Fuel), RDF (Waste Solidified Fuel), and building waste materials. By using such waste fuel, the unit price of fuel can be reduced to 1/5 to 1/10 compared to fossil fuel.

  In the kiln firing furnace 3, firing the granulated particles by holding the granulated particles at a firing temperature of 1050 to 1200 ° C. for 0.5 to 2 hours using waste fuel containing harmful heavy metals encloses the harmful heavy metals in the particles. Preferred above.

  If the firing temperature is maintained at 1050 to 1200 ° C. for less than 0.5 hours, harmful heavy metals cannot be contained in the particles, and firing unevenness will occur, and further increase in the effect can be expected even if the firing temperature exceeds 2 hours. Absent.

  The flow direction of the granulated particles and air in the kiln firing furnace 3 is preferably a co-current system in order to achieve the effects of the present invention.

  The combustion air ratio at the outlet of the kiln firing furnace 3 is preferably 1.0 or more in order to achieve complete combustion, and more preferably in the range of 1.3 to 1.5.

  Next, in FIG. 1, 5 is a post-combustion furnace. In the post-combustion furnace 5, combustion exhaust gas, granulated particles and 10-40 micron waste combustion ash discharged from the kiln firing furnace 3 are introduced. During this introduction, a part of the waste combustion ash adheres to the surface of the granulated particles.

  The shape of the post-combustion furnace 5 is not particularly limited, but a cylindrical frame melting furnace is preferably employed in the present embodiment.

  Combustion exhaust gas, granulated particles, and 10-40 micron waste combustion ash are introduced from the kiln calcining furnace 3 to the inlet portion 500 of the post-combustion furnace 5 and supplied with fossil fuels such as propane gas, city gas, and oil. Cause combustion.

  The inlet portion 500 of the post-combustion furnace 5 has a simple structure in which fuel such as propane or city gas is blown inward from the outer periphery, and a flame of 1300 to 1500 ° C. is formed from the tip of the inlet portion 500. The In this flame, 10-40 micron waste combustion ash is melted and spheroidized.

  Further, the flame is formed, and the waste combustion ash adhering to the surface of the granulated particles is melted at a temperature of 1300 to 1500 ° C.

  In the latter stage of the post-combustion furnace 5 after exiting the flame, it is mixed with cooling air and cooled and solidified to about 800 ° C. at the outlet of the melting furnace.

  Although not shown, the subsequent stage of the frame melting furnace 5 is divided into multiple stages, and cooling air is introduced from the fan 501 via the pipe 502 for each stage. An air introduction part 503 into which air is introduced via a pipe 504 is also formed at the bottom of the frame melting furnace 5. Reference numeral 505 denotes a spherical particle discharge unit. The discharged spherical particles are sent to the particle cooling unit 6.

  The particle cooling unit 6 can adopt, for example, a rotary drum type, and may be either direct cooling or indirect cooling. A cooling air pipe 600 is connected to the particle cooling unit 6.

  The inside of the particle cooling unit 6 is configured such that air (temperature about 150 ° C.) moves in the B direction and particles (about 800 ° C. at the inlet) move in the A direction, so that the cooling effect increases. This is preferable.

  The spherical particles cooled by the particle cooling unit 6 are cooled to about 50 to 150 ° C., discharged to the outside as a product 7 and stored.

  The air whose temperature has increased by contributing to cooling in the particle cooling section 6 is sent to the kiln firing furnace 3 and can be used as combustion air. At this time, since the temperature rises, there is an effect that the amount of starting oil used can be reduced.

  In the preferred embodiment of the present invention, fossil fuel is used in the post-combustion furnace 5, but since the temperature is raised to 1050 to 1200 ° C. in the kiln firing furnace 3, the amount of heat corresponding to a temperature increase of about 300 ° C. Only minutes are enough, and it has the effect of being economical.

  After the kiln calcining furnace 3 is partially melted in the surface portion of the granulated particles by passing through a high-temperature flame for a short time of 0.2 to 0.4 seconds, preferably in a post-combustion furnace. Because of cooling, not only firing unevenness can be eliminated, but also the strength of the spherical solidified product can be increased.

  Moreover, according to the preferable aspect of this invention, in the kiln baking furnace 3, the said granulated particle is hold | maintained at the calcination temperature of 1050-1200 degreeC for 0.5 to 2 hours using the waste fuel containing a toxic heavy metal. By calcination, harmful heavy metals are contained in the particles. Further, since the waste combustion ash adhering to the particle surface is also melted in the post-combustion furnace, harmful heavy metals can be contained in the cooled and solidified spherical particles to make them harmless.

  Furthermore, according to a preferred aspect of the present invention, the combustion air ratio in the kiln calcining furnace 3 is set to 1.0 or more so that the waste fuel is completely burned, and then propane or the like is introduced at the inlet of the post-combustion furnace 5. In order to increase the temperature of blowing and flame, the combustion air ratio is maintained at about 0.9 to 1.1. Downstream, cooling air is introduced stepwise to cool the exhaust gas to about 800 to 1000 ° C., so that complete combustion can be achieved with an air ratio of 1.3 or more.

  In the present invention, the obtained spherical solidified product is not required to be completely spherical, and may be substantially spherical. Substantially means that the variation in the ratio of orthogonal diameters is within ± 10%.

The waste combustion ash and the combustion exhaust gas of about 800 ° C. sucked by the suction fan 10 use an alkali spray such as slaked lime or sodium carbonate in the semi-dry type reaction cooling tower 8, for example, and the exhaust gas temperature is set to 150 to 200. Cool to 0 ° C. to remove HCl and SO ₂ that are corrosive components in the exhaust gas.

  Waste combustion ash and combustion exhaust gas treated in the reaction cooling tower 8 pass through the bag filter 9 to collect the waste combustion ash. The collected combustion ash is effectively used or landfilled. Moreover, combustion exhaust gas is discharged | emitted outside.

  Examples of the present invention will be described below, but the present invention is not limited to such examples.

Example 1
The elution test for harmful heavy metals of the granulated and fired product produced according to the present invention was analyzed according to the method of Environment Agency Notification No. 46 and compared with the soil environmental standards.

  Table 1 shows the results of the toxic heavy metal dissolution test of the granulated and fired product.

  From Table 1, it can be seen that the elution value of harmful heavy metals in the granulated and fired product satisfies the soil environmental standard value.

Example 2
The physical properties of the granulated product produced according to the present invention were measured, and the results are shown in Table 2.

  Crushing strength: A particle is placed on a compression tester, a load is applied to the substance, and the breaking strength is examined.

  From Table 2, since the granulated particles exhibit the physical properties as described above, they can be used as silica sand substitute particles for circulating fluidized bed boilers, as well as landfill substitutes, gravel substitutes, soil substitutes, etc. It can be seen that it can be used effectively.

Example 3
Hazardous heavy metal elution test of bag filter ash was conducted according to the method of Environment Agency Notification No. 46 and compared with the soil environment standard value.

  The results are shown in Table 3.

  From Table 3, it can be seen that the toxic heavy metal elution value of the bag filter ash meets the soil environmental standards.

Flow diagram showing preferred embodiments of the invention The figure which shows an example of the cutout part which concerns on this invention The figure which shows the other example of the cutout part which concerns on this invention Flow diagram showing a conventional example Cross-sectional view of a conventional flame melting furnace

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Ash granulator, stirring granulator 100: Granulation tank 101: Stirrer 102: Hopper 2: Cutting-out part 200: Input part 201: Screw feeder 202: Conveyor 3: Kiln baking furnace 300: Input part 301: Rotary valve 4: Waste fuel cutting section 400: Input section 401: Screw feeder 5: Post-combustion furnace 500: Inlet section 501: Fan 502: Piping 503: Air introduction section 504: Piping 505: Spherical particle discharge section 6: Particle cooling section 600 : Air piping 7: Product 8: Reaction cooling tower 9: Bag filter 10: Suction fan

Claims (8)

A granulation step of granulating fly ash into particles having a predetermined range of particle sizes by an ash granulator;
A firing step of introducing waste fuel containing granulated particles and harmful heavy metals granulated in the granulation step into a kiln firing furnace and firing at a firing temperature of 1050 to 1200 ° C;
Combustion exhaust gas, granulated particles and waste combustion ash discharged from the firing step are introduced into a downstream post-combustion furnace, and adhere to the surface of the granulated particles at a temperature of 1300 to 1500 ° C. at the front stage of the post-combustion furnace. The waste combustion ash is melted, cooling air is introduced at a later stage of the post-combustion furnace, and the granulated particles including the granulated particles in which the waste combustion ash exists in a molten state are cooled on the surface. And a post-combustion step for producing a substantially spherical solidified product.   10 to 50 micron fly ash collected after combustion in a circulating fluidized bed boiler in which the granulation step generates high-temperature and high-pressure steam by combustion heat obtained by burning fuel selected from biomass, various industrial wastes and fossil fuels 2. The method for producing granulated particles according to claim 1, wherein a raw material comprising water, water and cement is agitated and kneaded and granulated into particles of a predetermined size.   The method for producing granulated particles according to claim 1 or 2, wherein the waste fuel containing the toxic heavy metal used in the firing step is waste such as waste plastic, PRF, and building waste.   The said baking process hold | maintains the granulated material granulated by the said granulation process at the baking temperature of 1050-1200 degreeC for 0.5 to 2 hours, and baked. A method for producing granulated particles.   The method for producing granulated particles according to any one of claims 1 to 4, wherein a combustion air ratio at the exit of the kiln firing furnace is 1.0 or more.   The method for producing granulated particles according to any one of claims 1 to 5, wherein the theoretical air ratio after fossil fuel is blown at the entrance of the post-combustion furnace is maintained at 0.9 to 1.1. A granulator for granulating fly ash into particles having a predetermined particle size;
A kiln firing furnace for introducing waste containing granulated particles and harmful heavy metals granulated by the granulator and firing at a firing temperature of 1050 to 1200 ° C .;
The combustion exhaust gas, granulated particles, and waste combustion ash, which are disposed downstream of the kiln calcining furnace and discharged from the kiln calcining furnace, are introduced and adhered to the surface of the granulated particles at a temperature of 1300 to 1500 ° C. in the previous stage. The waste combustion ash is melted, cooling air is introduced at a later stage, and the granulated particles including the granulated particles in which the waste combustion ash exists in a molten state are cooled on the surface to form a substantially spherical shape. An apparatus for producing granulated particles, comprising a post-combustion furnace for producing a solidified product. The apparatus for producing granulated particles according to claim 7, wherein the post-combustion furnace is a flame melting furnace.

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