JP2005201594A - Waste incinerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste incinerator, preventing the occurrence of local high temperature and adhesion of dust to the inner wall of a furnace even if high-temperature gas is blown into a furnace. <P>SOLUTION: High-temperature combustion gas such as a burner combustion gas is introduced into a gas mixing device 24 through a high-temperature combustion gas regulator valve 26, and the air is also introduced through an air regulating valve 27. The high-temperature combustion gas and the air are mixed to generate high-temperature exhaust gas. The high-temperature exhaust gas is blown into a main combustion chamber 1. The high-temperature exhaust gas from the gas mixing device is blown into the main combustion chamber 1 through a rotary valve 25. With the rotation of a rotor of the rotary valve 25, pulsation is caused in the flow of the high-temperature exhaust gas. Thus, mixing of the high-temperature exhaust gas blown into the main combustion chamber 1 and the peripheral gas is accelerated to avoid the occurrence of local high temperature. Accordingly, the possibility of damaging the refractory material of the furnace is lowered and emission of dioxin and the like is restrained. Further NOx can be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a waste incinerator and a waste incinerator having a waste heat treatment furnace or an ash melting furnace as an accessory.

  In the waste incinerator with an ash melting furnace, the waste is incinerated in the main body of the waste incinerator, and the remaining ash is melted and discharged in the ash melting furnace. Such a waste incinerator is described in, for example, JP 2000-199619 A (Patent Document 1). The outline is shown in FIG. Garbage 42 charged in the hopper 41 is ignited and burned in the main combustion chamber 43 by hot air from below the grate or an auxiliary burner (not shown) installed in the main combustion chamber 43. The incinerated ash 44 generated by the combustion passes through the tapered flue 45 and enters the melting inappropriate material detection / removal unit 46. The inadequate melting object detection / removal unit 46 is provided with a detector for inadequate melting object and a device for discharging the detected inadequate melting object out of the furnace. The incinerated ash 44 from which the unsuitable melting material has been removed falls through the lattice 47, is melted in the ash melting furnace 48 to become molten slag 49, falls onto the slag conveyor 50, and is stored in the slag reservoir 51. Without providing the slag conveyor 50 and the slag reservoir 51, the molten slag can be dropped into water to form a granulated slag.

  A gas blowout port 60 is provided in the ash melting furnace 48, and as shown in the AA ′ cross-sectional view, the gas blowout port 60 has a combustible gas generated in the waste incinerator (incinerator). A mixture of unburned gas and hot air is blown into the furnace at high speed. Since the high-temperature gas mixture is blown in the tangential direction of the inner wall of the ash melting furnace 48 as seen in the AA ′ cross-sectional view, it is illustrated in the ash melting furnace 48 by the high-temperature gas mixture blown in. A swirling flame or a tubular flame is generated as described.

  Therefore, the inner wall of the furnace is heated almost uniformly by radiation from these flames or direct heat transfer. Therefore, the trouble of burning due to partial solidification of dust or slag or overheating of the inner wall is suppressed.

  An intermediate ceiling 56 is provided in the main combustion chamber 43, whereby the flow of exhaust gas is divided into two as shown by the arrows in the figure. The exhaust gas passing through the upper part of the intermediate ceiling 56 contains a lot of unburned gas, the exhaust gas passing through the lower part of the intermediate ceiling 56 contains a lot of unreacted oxygen, and these compositions are relatively stable.

  Most of the exhaust gas that bypasses the intermediate ceiling 56 is led to the secondary combustion chamber 57 where it is stirred by the stirring gas blown from the outlet 59 of the stirring gas in the furnace to become a swirling flow, and the secondary combustion is made efficient. Do it. Then, after heat exchange is performed by the exhaust heat boiler 58, most of the heat is sent to the dust remover 53 and the exhaust gas treatment device, and after dust and harmful substances are removed, it is dissipated from the chimney to the atmosphere.

  The high-temperature air blown into the ash melting furnace 48 is manufactured by heating air with a high-temperature air generator (not shown). Generally, fuel is burned and air is heated by the heat.

  In such a grate-type waste incinerator, when the waste is incinerated, it is difficult to maintain a constant combustion state in the furnace because the waste consists of many substances having different properties. It is inevitable that the temperature and combustion gas concentration distribution in the combustion chamber will be non-uniform in time and space.

  As a method for solving such a problem, Japanese Patent Application Laid-Open No. 11-2111044 (Patent Document 2) discloses a method in which high-temperature gas generated by a regenerative burner is blown into a main combustion chamber or a secondary combustion chamber of an incinerator. Is disclosed.

  Japanese Patent Application Laid-Open No. 11-223323 (Patent Document 3) discloses a method in which a high-temperature gas generated by a heat storage burner is blown into a furnace at a temperature of 800 ° C. or higher. All of these techniques are intended to reduce unburned gas and harmful substances containing a large amount of CO, aromatic hydrocarbons, and the like in exhaust gas generated in an incinerator.

JP 2000-199619 A JP 11-2111044 A JP-A-11-223323

  However, in some cases, blowing of an excessively high temperature gas into the furnace may cause a local high temperature portion, which may cause damage to the refractory or increase the amount of NOx gas generated. Further, when the furnace atmosphere exceeds 1000 ° C., dust tends to adhere to the furnace inner wall, and there is a problem that maintenance must be frequently performed for dust removal.

  The present invention has been made in view of such circumstances, and provides a waste incinerator in which local high temperature is not generated and dust does not adhere to the furnace inner wall even when high temperature gas is blown into the furnace. Is an issue.

  The first means for solving the problem is a waste incinerator having a function of blowing at least one of high temperature air or high temperature exhaust gas into the furnace, and the high temperature air or high temperature exhaust gas is accompanied by pulsation. A waste incinerator (Claim 1) characterized by being blown.

  In this means, high-temperature air or high-temperature exhaust gas is blown in with pulsation, so that mixing with the surrounding gas is promoted, generation of a local high-temperature region is prevented, and the furnace wall can be damaged. As well as reducing the property, it is possible to suppress the emission of CO and dioxins and the emission of NOx gas. In the present specification and claims, “high temperature exhaust gas” refers to combustion exhaust gas in which oxygen that still acts as an oxidant remains, or a mixture of combustion exhaust gas, air, and oxygen That is, it contains oxygen sufficient to act as an oxidant.

  The second means for solving the problem is a waste incinerator having a function of blowing at least one of high temperature air or high temperature exhaust gas into an ash heat treatment furnace or an ash melting furnace attached to the furnace, wherein the high temperature air Alternatively, the waste incinerator is characterized in that the high-temperature exhaust gas is blown in with pulsation (claim 2).

  Also in this means, the same effects as the first means can be obtained in the ash heat treatment furnace or ash melting furnace attached to the furnace.

  A third means for solving the problem is the first means or the second means, wherein the pulsation of the high-temperature air or the high-temperature exhaust gas is generated by a rotary valve. (Claim 3).

  In this means, the pulsation of high temperature air or high temperature exhaust gas is generated by the rotary valve, so the pulsation can be generated by a simple mechanism, there is little failure, and the equipment cost is reduced. be able to.

  A fourth means for solving the problem is the first means or the second means, wherein the pulsation of the high temperature exhaust gas is generated by generating the high temperature exhaust gas by combustion in a pulse burner. It is characterized by the above-mentioned (claim 4).

  In this means, the pulsation of the high-temperature exhaust gas is generated by generating the high-temperature exhaust gas by combustion with the pulse burner, so that the burner and the pulsation generator can be used together, and the equipment cost can be reduced. can do.

  The fifth means for solving the problem is the first means or the second means, and the pulsation of the high temperature air or the high temperature exhaust gas causes these gases to pass through the quarter wavelength tube. (Claim 5).

  A quarter-wave tube (Rijke Tube) generates air column vibrations by heating a quarter of the length from one end and cooling a quarter from the other end. Piping that can. In this means, strong pulsation can be generated without providing a movable part.

  As described above, according to the present invention, it is possible to provide a waste incinerator in which even when high temperature gas is blown into the furnace, local high temperatures are generated and dust does not adhere to the inner wall of the furnace.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of a waste incinerator as an example of an embodiment of the present invention. 1 is a main combustion chamber, and a hopper 2 for introducing waste 3 into the main combustion chamber 1 is provided on one side (left side in FIG. 1) of the main combustion chamber 1. Yes.

At the bottom of the main combustion chamber 1, a grate (stalker) that burns while moving the waste 3 is provided so as to be lowered as it moves away from the hopper 2. This grate has two steps and is divided into three parts. These three grates are called dry stoker 4, combustion stoker 5, and post-combustion stoker 6 from the side closer to hopper 2. In the dry stoker 4, the waste 3 is mainly dried and ignited. The combustion stoker 5 mainly burns the waste 3, but the waste 3 is burned and thermally decomposed, and unburned gas is released together with the combustion gas. Combustion of the waste 3 is substantially completed in the combustion stoker 5. On the post-combustion stoker 5, the remaining unburned matter in the waste 3 is completely burned. The combustion residue after complete combustion is discharged from the main ash chute 7.
A wind box 8 connected to a supply pipe for supplying combustion air is provided below each grate.

  A main flue 9 and a sub flue 10 are provided below and above the main combustion chamber 1 on the side opposite to the hopper 2, and a secondary combustion chamber 12 of the waste heat boiler 11 is connected to these. ing. In the main combustion chamber 1, a barrier (intermediate ceiling) 13 for diverting the combustion gas is provided in the vicinity of the outlet of the main combustion chamber 1, and the flow of the combustion gas is divided into the main flue 9 and the sub flue 10. It is divided into two.

As shown in FIG. 1, waste 3 is introduced from the hopper 2 into the main combustion chamber 1, and combustion air is supplied to the waste 3 moving on the grate through each supply pipe and the wind box 8. The waste 3 is dried and further combusted.
A nozzle 14 is provided on the side wall of the main combustion chamber 1, and high-temperature air or high-temperature exhaust gas (hereinafter referred to as “hot gas”) is blown into the main combustion chamber 1 from the nozzle 14.

  In FIG. 1, the nozzles 14 are installed on the upper part of the dry stalker 4 and the upper left part of the combustion stalker 5. When the waste 3 is incinerated, moisture first evaporates, and then thermal decomposition and partial oxidation occur. Here, the thermal decomposition reaction occurs at a temperature of about 200 ° C., and is almost completed when the temperature reaches about 400 ° C. In the example shown in FIG. 1, since it corresponds to the dry stoker 4 part (rear stage part) and the front stage part of the combustion stoker 5, this area is referred to as a combustion start area, and nozzles 14 are provided at these positions to blow in hot gas. It is out. Depending on the type of the waste 3, there are those in which the pyrolysis reaction is completed at a higher temperature. In this case, it is preferable to provide the nozzle 14 on the rear side (right side in the figure) from the position shown in FIG. 1.

  In FIG. 1, nozzles 14 are provided on both sides of the furnace, and hot gas is blown from here. The nozzle is preferably provided horizontally or downward. By doing so, the upward flow of the combustion air and pyrolysis gas (unburned gas) that has passed through the waste layer is blocked by the high-temperature gas to form a stagnation region. In order to promote the action of stopping the upward flow, it is preferable that the nozzle is provided downward. However, if the angle is set too much, the hot gas does not reach the entire furnace width direction. Therefore, it is particularly preferable that the angle is in the range of 10 to 20 degrees downward.

  In order to show the arrangement of the nozzles in FIG. 1, a cross-sectional view along A-A ′ is shown in FIG. 2. However, in FIG. 2, illustration of structures not related to the present invention is omitted. In FIG. 2, 15 is a stagnation region, 17 is a furnace wall, 18 is a furnace ceiling, 19 is a hot gas, and 21 is a pyrolysis gas.

  FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1, and the hot gas 19 blown out from the nozzle 14 provided downward on the furnace wall 17 on both sides is converted into the pyrolysis gas 21 and the combustion air. The upward flow is blocked and the stagnation region 15 where the flow stays slowly is shown. In the stagnation region 15, since the pyrolysis gas is blocked, a stable diffusion flame is formed and combustion is performed stably. Further, the waste is radiantly heated by the high-temperature gas, and thermal decomposition is promoted. As a result, unlike the prior art, instability of combustion in the combustion start region is not amplified even under low air ratio combustion conditions, soot generation is suppressed, and uniform and stable combustion can be expected.

  By blowing the hot gas with pulsation by means described later, the mixing of the hot gas and the surrounding gas is promoted, the generation of the local hot region is prevented, and the furnace wall is not damaged. At the same time, by reducing the temperature gradient in the vicinity of the inner wall, it is possible to prevent dust from adhering to or welding to the inner wall due to the thermophoretic effect. Moreover, generation | occurrence | production of NOx can be suppressed by preventing generation | occurrence | production of a local high temperature area | region.

  Further, since the hot gas is blown with pulsation, it is possible to increase the collision probability at the molecular level between oxygen in the hot gas and the fuel component in the pyrolysis gas. Emissions of fuel can be reduced.

  Moreover, as shown in FIG. 1, it is preferable to provide the nozzle 14 in the height position which does not exceed 1/2 of the main combustion chamber height. The reason is that the stagnation area can be made to be located immediately above the waste 3.

  Moreover, the combustion of the unburned gas can be promoted by blowing the high temperature gas into the space where the temperature is 400 ° C. or higher and the unburned gas exists. Therefore, the nozzle is arranged so that the hot gas is blown into the region where the sub flue gas containing a large amount of unburned gas and the main flue gas are mixed, that is, above the intermediate ceiling 13 and into the entrance of the secondary combustion chamber 12. You may provide in a side wall, a ceiling, the intermediate | middle ceiling 13, and the secondary combustion chamber 12 entrance.

  Moreover, although the furnace which has the intermediate ceiling 13 is illustrated in FIG. 1, it cannot be overemphasized that this invention is applicable also to the furnace which does not have such an intermediate ceiling.

  In FIG. 1, the hot gas is blown into the main combustion chamber 1, but the hot gas may be blown into the gas mixing section in the secondary combustion chamber 12. Further, the hot gas may be blown from one side surface of the furnace. Furthermore, you may make it blow in from an intermediate | middle ceiling or a ceiling instead of from the side surface of a furnace.

  FIG. 3 shows an outline of a high-temperature exhaust gas blowing system in a waste incinerator as an example of an embodiment of the present invention. As shown in detail in FIG. 1, the exhaust gas from the main combustion chamber 1 is guided to the waste heat boiler 11, and after secondary combustion in the secondary combustion chamber 12, which is a part of the exhaust gas, heat exchange is performed in the waste heat boiler 11. After being purified by the exhaust gas treatment facility 22, it is emitted from the chimney 23 to the atmosphere.

  In this embodiment, air and high-temperature combustion gas are mixed by the gas mixing device 24. A high-temperature combustion gas such as a burner combustion gas is introduced into the gas mixing device 24 via a high-temperature combustion gas control valve 26 and air is introduced via an air control valve 27.

  The gas mixing device 24 mixes high-temperature combustion gas and air to generate high-temperature exhaust gas. This high temperature exhaust gas is blown into the main combustion chamber 1. The oxygen concentration in the high-temperature exhaust gas is adjusted by the oxygen concentration adjusting device 29. The oxygen concentration adjusting device 29 adjusts the opening degree of the air control valve 27 so that the oxygen concentration of the high-temperature exhaust gas blown into the furnace becomes a predetermined concentration. Further, the temperature of the high temperature exhaust gas is adjusted by the temperature adjustment device 28. The temperature control device 28 adjusts the opening degree of the high-temperature combustion gas control valve 26 so that the temperature of the high-temperature exhaust gas falls within a predetermined range.

  The high temperature exhaust gas exiting the gas mixing device 24 is blown into the main combustion chamber 1 via the rotary valve 25. As the rotor of the rotary valve 25 rotates, pulsation occurs in the flow rate of the high-temperature exhaust gas. As a result, the mixing of the high-temperature exhaust gas blown into the main combustion chamber 1 and the surrounding gas is promoted, and the occurrence of local high temperatures is avoided. Therefore, the possibility of damaging the refractory on the furnace wall is reduced, the discharge of CO and dioxins is suppressed, and the NOx can be reduced.

Moreover, since the temperature gradient in the vicinity of the inner wall of the furnace is reduced, the thermophoresis effect of dust is reduced, and as a result, the degree of dust adhering to the furnace wall is reduced.
In the example shown in FIG. 3, temperature control and oxygen concentration control of the hot exhaust gas to be blown are performed, but these controls are not necessarily required.

FIG. 4 shows an outline of a high-temperature exhaust gas blowing system in a waste incinerator as another example of the embodiment of the present invention. The example shown in FIG. 4 differs from the example shown in FIG. 3 only in that a quarter-wave tube is used instead of a rotary valve in order to give pulsation to the hot exhaust gas that is blown, and the others are the same. Therefore, in the example shown in FIG. 4, the pipe 30 between the gas mixing device 24 and the main combustion chamber 1 constitutes a quarter wavelength tube. That is, the position of 1/4 length from one end of this pipe is heated, and the position of 1/4 length from the other end is cooled. As a result, air column vibrations are generated in the pipe 30 and the pressure and flow rate of the high-temperature exhaust gas passing through the pipe 30 pulsate. Thereby, the same effect as the example shown in FIG. 3 can be acquired.

  In the examples shown in FIGS. 3 and 4, exhaust gas circulation may be performed by mixing a part of the exhaust gas of the incinerator with the high temperature exhaust gas. 3 and 4, the gas mixing device 24, the rotary valve 25, and the quarter wavelength tube 30 are not provided, and the mixed gas of air and fuel is put into a pulse burner to perform pulse combustion, and the pulsation generated as a result is detected. You may make it blow in the hot exhaust gas which it had.

  Further, in the examples shown in FIGS. 3 and 4, high-temperature combustion gas and air are mixed to produce high-temperature exhaust gas having an ability as an oxidant. Air may be blown in. Alternatively, a high temperature combustion gas and oxygen may be mixed and blown.

  Although not shown, pulsation is given to the high-temperature air blown into the ash melting furnace 48 or the ash heat treatment furnace as shown in FIG. 5 through a rotary valve or a quarter wavelength tube. Is preferred. As a result, mixing of gas in the furnace is promoted, generation of a local high temperature region is prevented, and damage to the furnace wall and generation of NOx can be prevented. Further, it is possible to prevent dust from adhering to and welding on the inner wall of the furnace. Furthermore, even if a low-calorie gas such as an unburned incinerator gas is used as fuel, agitation with high-temperature air is performed, so that stable combustion is possible.

It is a figure which shows the example of the waste incinerator which implements the operating method of the waste incinerator which is an example of embodiment of this invention. FIG. 2 is a cross-sectional view taken along line A-A ′ in order to show the arrangement of nozzles in FIG. 1. It is a figure which shows the outline | summary of the high temperature exhaust gas blowing system | strain in the waste incinerator which is an example of embodiment of this invention. It is a figure which shows the outline | summary of the high temperature exhaust gas blowing system | strain in the waste incinerator which is another example of embodiment of this invention. It is a figure which shows the outline | summary of the conventional waste incinerator with an ash melting furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main combustion chamber, 2 ... Hopper, 3 ... Waste, 4 ... Dry stoker, 5 ... Combustion stoker, 6 ... Post combustion stoker, 7 ... Main ash chute, 8 ... Wind box, 9 ... Main flue, 10 ... Secondary flue, 11 ... Waste heat boiler, 12 ... Secondary combustion chamber, 13 ... Intermediate ceiling, 14 ... Nozzle, 15 ... Stagnation region, 17 ... Furnace wall, 18 ... Furnace ceiling, 19 ... Hot gas, 21 ... Thermal decomposition Gas, 22 ... Exhaust gas treatment equipment, 23 ... Chimney, 24 ... Gas mixing device, 25 ... Rotary valve 26 ... High-temperature combustion gas control valve, 27 ... Air control valve, 28 ... Oxygen concentration control device, 29 ... Temperature control device, 30 ... Piping (1/4 wavelength tube)

Claims (5)

A waste incinerator having a function of blowing at least one of high-temperature air or high-temperature exhaust gas into the furnace, wherein the high-temperature air or high-temperature exhaust gas is blown with pulsation Incinerator. A waste incinerator having a function of blowing at least one of high-temperature air or high-temperature exhaust gas into an ash heat treatment furnace or ash melting furnace attached to the furnace so that the high-temperature air or high-temperature exhaust gas is blown with pulsation Waste incinerator characterized by being. The waste incinerator according to claim 1 or 2, wherein pulsation of the high-temperature air or high-temperature exhaust gas is generated by a rotary valve. The waste incinerator according to claim 1 or 2, wherein the pulsation of the high temperature exhaust gas is generated by generating the high temperature exhaust gas by combustion in a pulse burner. The waste incineration according to claim 1 or 2, wherein the pulsation of the high-temperature air or the high-temperature exhaust gas is generated by passing these gases through a quarter-wave tube. Furnace.

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