JP3909661B2 - Waste plastic blowing equipment into lime furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for injecting waste plastic into a lime furnace that injects waste plastic as fuel into a lime furnace for firing raw stones such as limestone and dolomite.
[0002]
[Prior art]
A Merz furnace is known as a lime furnace for firing raw stones such as lime and dolomite. A Merz furnace uses two shafts to fire the rough. 12 and 13 show a swing burner provided on the shaft of the Merz furnace. As shown in this figure, a burner arch 1 is provided at the boundary between the pre-tropical zone and the calcined zone of each shaft, and the swing swings into a V-shaped combustion space 2 formed by the burner arch 1 and the angle of repose of the rough stone. Burner 3 is inserted. Three holes for blowing heavy oil are formed at the tip of the swing burner 3.
[0003]
FIG. 14 shows the distribution trajectory of heavy oil on the rough stone surface. By turning the swing burner 3 about the axis, heavy oil is sprayed in the form of three lines 4. Thereby, heavy oil fully covers the whole cross-sectional area of a baking zone. The sprayed heavy oil hardly evaporates in the combustion space 2, and most of the heavy oil comes into contact with the heated limestone and evaporates. And it burns in the space between the rough stones in the firing zone.
[0004]
In recent years, there has been a demand for replacement of heavy oil by cheap waste plastic with the aim of reducing fuel costs. Waste plastic is used plastic contained in general waste discarded from households or industrial waste discarded from factories. The main product is a molded product obtained by extruding a film-like plastic or crushed plastic, or a crushed product obtained by crushing hard plastic, and the particle size is under 10 mm.
[0005]
As a technology for effectively using this waste plastic as an alternative to heavy oil, the present applicant has proposed a method for producing lime by gasifying the waste plastic in a fluidized bed furnace, feeding this gas into a Merz furnace, and firing the lime. (See Japanese Patent Application Laid-Open No. 2001-72446).
[0006]
In addition, as a technology for effectively using waste plastic as an alternative to heavy oil, the present applicant also proposes a technology that provides a blow lance for blowing waste plastic into the firing zone of the Merz furnace, and blows granular waste plastic into the rough from this blow lance. (Refer to Japanese Patent Laid-Open No. 11-263641).
[0007]
[Problems to be solved by the invention]
In the method for producing lime described in Japanese Patent Application Laid-Open No. 2001-72446, when waste plastic is blown into the Merz furnace in granular form by sending it to a lance furnace after gasifying the waste plastic Compared with, waste plastic can be used more effectively. However, a fluidized bed furnace for gasifying waste plastic is required.
[0008]
In addition, in the technology of providing a blowing lance for blowing waste plastic into the firing zone of the Merz furnace, there is a risk that sufficient space for blowing an appropriate amount of waste plastic into the furnace will not be secured and gasification of the waste plastic will not be performed sufficiently. For this reason, there is a possibility that the amount of heat of the waste plastic cannot be effectively utilized.
[0009]
Therefore, the present invention provides a lime furnace for firing raw stones such as lime or dolomite, especially lime that can be blown with simple equipment when the waste plastic is blown into a Merz furnace, and the amount of heat of the waste plastic can be used sufficiently effectively. The object is to provide an apparatus for blowing waste plastic into a furnace.
[0010]
[Means for Solving the Problems]
The present applicant has paid attention to the fact that a refractory burner arch is provided in a swing burner furnace of a Merz furnace, and a combustion space in a high-temperature atmosphere is created under the burner arch. This combustion space is formed in a substantially V-shaped cross section by the lower surface of the burner arch and two slopes formed by the angle of repose of the raw stone. Combustion air preheated to about 1000 ° C. in the pre-tropical zone flows into the combustion space, and a part of heavy oil combustion heat is added to the combustion space, so that the combustion space has a high temperature atmosphere of 1000 to 1100 ° C. It has been found that if waste plastic is blown into the uppermost stream of the rough surface of the rough stone that forms the combustion space in this high-temperature atmosphere, the waste plastic can be smoothly gasified and the amount of heat of the waste plastic can be used effectively.
[0011]
That is, the invention according to claim 1 is provided with a blowing nozzle for blowing waste plastic into a combustion space having a substantially V-shaped cross section formed by the angle of repose of the raw stone under the burner arch of the lime furnace, In the apparatus , the blowing nozzle blows waste plastic into the uppermost stream portion of the inclined surface of the rough stone forming the combustion space, and the blowing nozzle is composed of a plurality of embedded nozzles embedded in the burner arch, and the plurality of embedded nozzles nozzle, above the disposed at both ends in the width direction of the combustion space, moreover characterized in that it is spaced substantially equally spaced in the depth direction of the combustion space, the injectors of the waste plastics into the lime kiln Solve the problem.
[0012]
According to the present invention, waste plastic can be gasified with simple equipment without providing a separate fluidized bed furnace or the like. In addition, since the waste plastic is blown into the combustion space under the burner arch of the lime furnace, the waste plastic can be smoothly gasified in a high temperature atmosphere, and the amount of heat of the waste plastic can be used effectively.
[0013]
By the way, when the waste plastic is blown onto the surface of the rough stone in the V-shaped combustion space, the waste plastic is uniformly sprayed on the surface of the rough stone as in the case of spraying heavy oil with a conventional swing burner, as shown in FIG. Thus, due to the synergistic effect of the rolling and falling movement of the rough surface and the flow of combustion air, the sprayed waste plastic falls and accumulates in a V-shaped valley. This variation in waste plastic accumulation causes uneven burning between the center side and the outside of the furnace, and causes the problem that unburned rough remains on the outside of the center side where it is overburned.
[0015]
According to this invention, the rolling of raw stone, the stirring by combustion air, and the flow of air-fed air of waste plastic are combined, and the sprayed waste plastic is deposited uniformly on the slope without being deposited in the valleys.
[0019]
According to the present invention, since the embedded nozzle is embedded in the refractory burner arch, it is not directly exposed to a high temperature, and the lifetime of the embedded nozzle can be extended. Further, the waste plastic can be uniformly deposited over the entire slope of the combustion space.
[0020]
According to a second aspect of the present invention, there is provided an apparatus for injecting waste plastic into limestone, wherein a blow nozzle for injecting waste plastic is provided in a combustion space having a substantially V-shaped cross section formed by the angle of repose of the raw stone under the burner arch of the lime furnace. The blowing nozzle blows waste plastic into the uppermost stream portion of the inclined surface of the rough stone forming the combustion space, and the blowing nozzle penetrates the side wall of the lime furnace forming the combustion space, It is composed of a plurality of side wall penetrating nozzles extending in the depth direction, and the front end portions of the plurality of side wall penetrating nozzles face the width direction of the combustion space so that waste plastic can be blown into the uppermost stream portion of the inclined surface of the raw stone, The tip portions of the plurality of side wall penetrating nozzles are characterized in that their positions in the depth direction of the combustion space can be adjusted.
[0021]
According to the present invention , waste plastic can be gasified with simple equipment without providing a separate fluidized bed furnace or the like. In addition, since the waste plastic is blown into the combustion space under the burner arch of the lime furnace, the waste plastic can be smoothly gasified in a high temperature atmosphere, and the amount of heat of the waste plastic can be used effectively. Further, it is possible to uniformly disperse the waste plastic over the entire slope of the combustion space. Furthermore, by adjusting the position of the front end portion of the side wall penetrating nozzle in the depth direction of the combustion space, the heat quantity distribution in the firing zone cross-sectional direction can be adjusted.
[0022]
According to a third aspect of the present invention, there is provided an apparatus for blowing waste plastic into limestone, wherein a blow nozzle for blowing waste plastic is provided in a combustion space having a substantially V-shaped cross section formed by an angle of repose of a raw stone under a burner arch of a lime furnace. The blowing nozzle blows waste plastic into the uppermost stream portion of the inclined surface of the rough stone forming the combustion space, and the blowing nozzle penetrates the side wall of the lime furnace forming the combustion space, It is composed of a plurality of movable nozzles extending in the depth direction, and the tip of the movable nozzle faces the width direction of the combustion space so that waste plastic can be blown into the uppermost stream portion of the inclined surface of the raw stone, The reciprocating motion is possible in the depth direction of the combustion space.
[0023]
According to the present invention , waste plastic can be gasified with simple equipment without providing a separate fluidized bed furnace or the like. In addition, since the waste plastic is blown into the combustion space under the burner arch of the lime furnace, the waste plastic can be smoothly gasified in a high temperature atmosphere, and the amount of heat of the waste plastic can be used effectively. In addition, the waste plastic can be deposited uniformly over the entire slope of the combustion space.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a swing burner furnace of a Merz furnace to which a blowing device for a lime furnace of the present invention is applied. First, the structure of the Merz furnace will be described. The Merz furnace has two or three (two in this embodiment) shafts 11 and 12, and these shafts 11 and 12 are alternately used by the turning device 13. The rough is charged from the top of the Merz furnace. The raw stone descends the shaft and sequentially passes through a pre-tropical zone for preheating the raw stone, a firing zone for firing the raw stone, and a cooling zone for cooling the fired raw stone. Then, it is discharged from the lower portion of the shaft by the discharge device 14.
[0025]
The shells of the shafts 11 and 12 are made of steel, and the inside is lined with refractory bricks and heat insulation bricks. The shafts 11 and 12 are connected by a channel 15 below the firing zone. The channel 15 is at the junction of the calcining zone and the cooling zone, and serves as a communication port through which the combustion gas and cooling air that have descended the calcining zone merge and flow into the other shaft.
[0026]
A raw material charging apparatus for charging raw materials to each shaft includes a lower throat 16 coupled to both shafts 11 and 12 and an upper throat 17 that rotates up and down by hydraulic pressure or the like. Combustion air is sent from the blower 18 through the duct 19 to the center of the lower throat 16 and enters one of the two shafts (for example, 11) according to the direction of the upper throat 17. The opposite shaft 12 is coupled to the chimney 20 at the upper throat 17. The measured rough is supplied to the shaft 11 opposite to the combustion side through the lower part of the chimney 20 by opening and closing the charging gate 21 from the service hopper. The exhaust gas is discharged from the chimney 20 through the throats 16 and 17 from the shaft 11 on the raw stone charging side. When the combustion for a certain time is finished, the switching of the upper throat 17 starts, the ascent, the rotation of 180 ° and the descent are finished, and the raw stone is charged in the reverse direction and the combustion air is blown.
[0027]
As described above, the Merz furnace is a parallel flow heat storage system that includes two shafts and performs firing while alternately exchanging the combustion side shaft and the preheating side shaft at a constant cycle. The rough stone is charged into the preheating side shaft 11. In the combustion side shaft 12, fuel is combusted by the combustion air blown from the top of the shaft, and the raw stone is fired in parallel flow by the hot gas. The combustion gas descends in the direction of the channel 15, merges with the cooling air blown from below the combustion side shaft 12, and enters the preheating side shaft 11 through the channel 15. The hot gas that has entered the preheating-side shaft 11 is baked with the charge in the firing zone, and at the same time, the pretropical rough is preheated and discharged from the top of the shaft as exhaust gas.
[0028]
When such firing is completed for a certain period of time, the supply of heavy oil, combustion air, and cooling air into the shaft and the product discharge device are temporarily stopped, and the throat rotates 180 ° to switch to shaft combustion on the opposite side.
[0029]
A burner arch 22 is provided at the boundary between the pre-tropical zone and the firing zone of each shaft, and a swing burner 23 is installed below the burner arch 22. Fuel such as heavy oil is swing-injected onto the rough stone surface.
[0030]
FIG. 2 shows the flow of combustion air and the movement of the raw stone in the combustion space S having a substantially V-shaped cross section under the burner arch. The combustion space S is formed by two slopes created by the lower surface of the refractory burner arch and the angle of repose of the rough.
[0031]
When the raw stone is limestone, the V-shaped opening angle formed by both slopes of the limestone is about 100 °. The raw stone descends in the furnace while being fired by the operation of the discharge device 14 provided in the lower part of the furnace. The raw stone existing on the slope of the combustion space S also descends in the same manner, but the new raw stone rolls down from the upper part of the burner arch and is supplemented (see arrow B in the figure), so that the V-shaped combustion space S is maintained. On the other hand, the combustion air is heated to around 1000 ° C. in the pretropical zone, passes through the burner arch, and flows down to the firing zone. Part of it flows into the V-shaped combustion space S, and again flows into the raw stone packed bed of the calcined zone while starting combustion with part of the heavy oil (see arrow A in the figure). Since the combustion air preheated to around 1000 ° C. flows into the combustion space S and a part of the heat of combustion of the heavy oil is added, the combustion space S becomes a high temperature atmosphere of 1000 to 1100 ° C. The pressure in the combustion space S is a positive pressure of about 3000 mmH ₂ O.
[0032]
The apparatus for blowing waste plastic into the lime furnace according to the present invention blows waste plastic that is aired (air conveyed) into the combustion space S in a high temperature atmosphere. As a result, the waste plastic is smoothly gasified in the combustion space S, and the amount of heat of the waste plastic is sufficiently effectively used.
[0033]
3 and 4 show a first embodiment of a waste plastic blowing apparatus according to the present invention. The blowing nozzle 25 that blows the waste plastic into the combustion space S passes through the side wall of the furnace in the range of the burner arch 22 in the height direction, and is bent so that the tip side thereof is directed vertically downward from the horizontal direction in the vicinity of the burner arch 22. The blowing nozzle 25 facing vertically downward is embedded in the burner arch 22. The front end sides 25a of the plurality of blowing nozzles embedded in the burner arch (described as embedded nozzles in the claims) are arranged at the center of the combustion space S in the width direction (left and right direction (1) in the figure). Further, they are arranged at both ends, and are arranged at substantially equal intervals in the depth direction of the combustion space (direction perpendicular to the paper surface in FIG. 3). The number of the embedding nozzles 25a is set to a minimum that enables uniform spraying in the vicinity of both ends in the width direction of the combustion space S and in the depth direction of the combustion space S. The waste plastic is metered and controlled to an arbitrary supply amount outside the furnace, is pneumatically conveyed by air feeding, and is blown out from the embedded nozzle 25a. The material of the embedding nozzle 25a is made of heat-resistant steel or ceramics, and its pipe diameter is set to about 32 to 40 A so that it can be conveyed without clogging the waste plastic under 10 mm.
[0034]
FIG. 5 shows the movement of the waste plastic particles blown from the embedded nozzle 25a. By blowing waste plastic from the uppermost stream part of the rough surface of the rough stone that forms the combustion space S, the raw stone rolls, agitates by the combustion air, and the downward flow of the waste plastic carrier air is uniformly discarded on the inclined surface. Plastic particles are dispersed. Dispersed waste plastics are gasified in a high-temperature atmosphere in the combustion space through a process of raising temperature → melting → decomposition → vaporization. Most of the waste plastic is gasified and then penetrates into the packed bed of raw stone to ignite and burn.
[0035]
On the other hand, for example, when waste plastic is spread evenly on an inclined surface using a swing burner, the valley of the V-shaped combustion space is caused by the synergistic effect of rolling the raw stone, stirring with combustion air, and downward flow of waste plastic conveyance air. Falls and accumulates on the surface. As a result, there is a risk that the unevenness of the rough stone will occur between the inside and outside of the furnace.
[0036]
In the first embodiment, all the blowing nozzles 25 pass through the side wall (lateral) of the shaft and extend in the horizontal direction toward the burner arch 22. May extend vertically to the burner arch 22 and pass through the burner arch 22 without bending (see a two-dot chain line in FIG. 3). When the blowing nozzles 25 'are arranged in this way, the blowing nozzle 22 does not hinder the flow of the rough.
[0037]
6 and 7 show a second embodiment of the waste plastic blowing apparatus according to the present invention. In this embodiment, the blowing nozzle is constituted by a plurality of side wall penetrating nozzles 26 that penetrate the upper part of the side wall 27 of the lime furnace that forms the combustion space and extend in the depth direction 2 of the combustion space. The front end portions 26a of the plurality of side wall penetrating nozzles 26 are bent so that the waste plastic can be blown into the uppermost stream portion of the inclined surface of the raw stone, and face the width direction (horizontal direction) of the combustion space. Further, the position of the side wall penetrating nozzle 26 in the axial direction can be adjusted, and thereby the positions of the tip portions 26a of the plurality of side wall penetrating nozzles 26 in the depth direction of the combustion space S can be adjusted. The number of the plurality of side wall penetrating nozzles 26 is set to a minimum that enables uniform spraying in the depth direction of the combustion space S. The waste plastic is metered to an arbitrary supply amount outside the furnace, and is blown out from the front end portion 26a of the side wall through nozzle 26 by air feeding. For the material of the side wall penetrating nozzle 26, heat-resistant steel or ceramics is used.
[0038]
FIG. 8 shows the movement of the waste plastic particles blown out from the front end of the through-wall nozzle 26. As shown in this figure, the waste plastic is blown into the uppermost stream portion of the rough surface of the rough, so that the raw stone rolls and the agitation by the combustion air is combined to uniformly disperse the particles of the waste plastic. Further, by adjusting the position of the front end portion 26a of the side wall penetrating nozzle 26 in the depth direction 2 of the combustion space S, the heat amount distribution in the depth direction of the firing zone can be adjusted.
[0039]
9 and 10 show a third embodiment of the waste plastic blowing apparatus according to the present invention. In this embodiment, the blowing nozzle is constituted by a pair of movable nozzles 28 that penetrate the upper part of the side wall 27 of the lime furnace that forms the combustion space S and extend in the depth direction 2 of the combustion space S. One movable nozzle 28 penetrates the side wall on the near side of the combustion space S, and the other movable nozzle 28 penetrates the side wall on the far side of the combustion space. The distal end portion 28a of the movable nozzle 28 faces in the width direction 1 (horizontal direction) of the combustion space so that plastic can be blown into the uppermost stream portion of the inclined surface of the raw stone. That is, the planar shape of the movable nozzle 28 is formed in a T shape. The movable nozzle 28 can reciprocate in the depth direction 2 of the combustion space S. The reciprocating speed is preferably 1 to 3 m / min, and the speed can be adjusted. Waste plastic is metered to an arbitrary supply amount outside the furnace, and is blown out from the front end portion 28a of the movable nozzle 28 by air feeding. The material of the movable nozzle 28 is heat resistant steel or ceramics.
[0040]
FIG. 11 shows the movement of the waste plastic particles blown from the tip 28 a of the movable nozzle 28. By blowing waste plastic into the uppermost stream portion of the rough surface of the rough stone, the roll of the rough stone and the stirring by the combustion air are combined to uniformly disperse the particles of the waste plastic.
[0041]
The waste plastic may be blown in parallel with the heavy oil sprayed from the swing burner 23, or may be blown as an alternative to 100% heavy oil. When the waste plastic is blown in parallel with the heavy oil, it is desirable to blow the waste plastic to the uppermost stream portion of the rough surface of the rough stone that forms the V-shaped combustion space as in the above embodiment, The waste plastic may be sprayed toward the V-shaped valley of the combustion space to prevent burning unevenness.
[0042]
The apparatus for injecting waste plastic into the lime furnace of the present invention can be applied not only to the above-mentioned Merz furnace but also to a Merz furnace with a side burner in which an auxiliary burner is attached to the lower part of the Merz furnace. In a Merz furnace with a side burner, an auxiliary burner is attached to the lower side wall of the furnace and auxiliary combustion is performed to average the furnace temperature between the inside and outside of the furnace, thereby eliminating unburned parts.
[0043]
【The invention's effect】
As described above, according to the present invention, the waste plastic is blown into the combustion space having a substantially V-shaped cross section formed by the angle of repose of the raw stone under the burner arch of the lime furnace, so a separate fluidized bed furnace is provided. The waste plastic can be blown in easily. In addition, since the waste plastic is blown into the combustion space under the burner arch of the lime furnace, the waste plastic can be smoothly gasified in a high temperature atmosphere, and the amount of heat of the waste plastic can be used effectively.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a Merz furnace to which a waste plastic blowing device is applied to a lime furnace of the present invention.
FIG. 2 is a diagram showing the flow of combustion air and the movement of limestone in the combustion space.
FIG. 3 is a view showing a first embodiment of a waste plastic blowing apparatus according to the present invention.
4 is a cross-sectional view taken along line AA in FIG.
5 is a partially enlarged view of FIG. 3, showing the movement of waste plastic particles in the combustion space.
FIG. 6 is a view showing a second embodiment of the waste plastic blowing apparatus of the present invention.
7 is a cross-sectional view taken along line AA in FIG.
8 is a partially enlarged view of FIG. 6 showing the movement of waste plastic particles in the combustion space.
FIG. 9 is a view showing a third embodiment of the waste plastic blowing apparatus of the present invention.
10 is a cross-sectional view taken along line AA in FIG.
11 is a partially enlarged view of FIG. 9 showing the movement of waste plastic particles in the combustion space.
FIG. 12 is a vertical sectional view of a shaft of a Merz furnace.
13 is a cross-sectional view taken along line AA in FIG.
FIG. 14 is a plan view showing a heavy oil spraying locus.
FIG. 15 is a view showing an example of spraying waste plastic with a swing burner.
[Explanation of symbols]
22 Burner arch 25 Embedded nozzle (blowing nozzle)
26 Side wall through nozzle (blowing nozzle)
27 Side wall 28 Movable nozzle (blowing nozzle)
S Combustion space

Claims (3)

In an apparatus for blowing waste plastic into limestone, in which a blowing nozzle for blowing waste plastic is provided in a combustion space having a substantially V-shaped cross section formed by the angle of repose of the raw stone under the burner arch of the lime furnace,
The blowing nozzle blows waste plastic into the uppermost stream part of the inclined surface of the rough stone forming the combustion space, and the blowing nozzle is composed of a plurality of embedded nozzles embedded in the burner arch, and the plurality of embedded nozzles are An apparatus for blowing waste plastic into a lime furnace, which is disposed at both ends in the width direction of the combustion space and is disposed at substantially equal intervals in the depth direction of the combustion space . In an apparatus for blowing waste plastic into limestone, in which a blowing nozzle for blowing waste plastic is provided in a combustion space having a substantially V-shaped cross section formed by the angle of repose of the raw stone under the burner arch of the lime furnace,
The blowing nozzle blows waste plastic into the uppermost stream portion of the inclined surface of the raw stone forming the combustion space, and the blowing nozzle penetrates the side wall of the lime furnace forming the combustion space, and the depth direction of the combustion space A plurality of side wall penetrating nozzles extending in the direction of the combustion space, and tip portions of the plurality of side wall penetrating nozzles face in the width direction of the combustion space so that waste plastic can be blown into the uppermost stream portion of the inclined surface of the raw stone, An apparatus for blowing waste plastic into a lime furnace is characterized in that the position of the tip of the side wall penetrating nozzle in the depth direction of the combustion space can be adjusted . In an apparatus for blowing waste plastic into limestone, in which a blowing nozzle for blowing waste plastic is provided in a combustion space having a substantially V-shaped cross section formed by the angle of repose of the raw stone under the burner arch of the lime furnace,
The blowing nozzle blows waste plastic into the uppermost stream portion of the inclined surface of the raw stone forming the combustion space, and the blowing nozzle penetrates the side wall of the lime furnace forming the combustion space, and the depth direction of the combustion space The movable nozzle has a front end facing the width direction of the combustion space so that waste plastic can be blown into the uppermost stream portion of the inclined surface of the raw stone. A device for blowing waste plastic into a lime furnace, which is capable of reciprocating in the depth direction of the combustion space .

Images