JP2002323208A - Method for operating incinerator, and the incinerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for operating an incinerator and an incinerator, capable of using heat generated by burning unburned gas in a combustion chamber for multi-purposes. SOLUTION: A part of unburned gas in the combustion chamber, extracted by an ejector, is burnt in the ejector and the heat generated by the combustion is used as a heat supply source. The incinerator has one end side connected to an upstream side area in the combustion chamber, and the other end side provided with gas supply piping connected to the upper area of a post-burnt fire grate and the ejector provided on the way of the gas supply piping for burning a part of the unburned gas, extracted from the upstream side area in the combustion chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating an incinerator for incinerating waste such as municipal waste and an incinerator.

[0002]

2. Description of the Related Art Grate-type waste incinerators are widely used as incinerators for incinerating waste such as municipal waste.
In such an incinerator, the incinerated material on the grate is dried, gasified, and burned by an oxidant supplied into the combustion chamber from below the grate. Combustion gas containing a large amount of reducing unburned gas such as carbon monoxide and hydrocarbons generated by gasification of the incinerated material on the upstream grate in the combustion chamber rises in the combustion chamber and rises on the ceiling of the combustion chamber. Follow along to the combustion chamber exit. In addition, the combustion gas generated from the incineration material on the downstream grate in the combustion chamber rises in the combustion chamber, and flows to the outlet of the combustion chamber along the ceiling of the combustion chamber in the opposite direction to the combustion gas generated from the upstream side. move on. The combustion gas from the upstream side and the combustion gas from the downstream side are mixed and agitated in a stagnation space near the outlet of the combustion chamber, and reburned. At this time, an oxidizing agent for reburning is supplied into the combustion chamber, and the combustion gas is reburned to completely burn unburned components in the combustion gas. Exhaust gas after re-combustion, that is, exhaust gas discharged from the combustion chamber outlet, flows into a boiler section connected to the downstream side of the combustion chamber outlet, undergoes heat exchange and is cooled, and then passes through an exhaust gas treatment facility or the like. Released outside.

[0003] As described above, the combustion gas containing a large amount of reducing unburned gas such as carbon monoxide and hydrocarbon generated by gasification of the incinerated material on the upstream grate in the combustion chamber is:
The unburned portion is completely burned by the reburning, and a part of the heat generated at that time is recovered in the boiler section.

[0004]

As described above, in the prior art, the combustion gas containing a large amount of the reducing unburned gas such as carbon monoxide and hydrocarbons generates heat generated by reburning the boiler. It was not used for any other purpose except for collection in the department.

Accordingly, an object of the present invention is to provide an incinerator operating method and an incinerator that can use heat generated by burning unburned gas in a combustion chamber for a multipurpose as a heat supply source. .

[0006]

The features of the present invention for solving such a problem are as follows.

The invention according to claim 1 is characterized in that a part of the unburned gas in the combustion chamber extracted by the ejector is burned in the ejector, and the heat generated by the combustion is used as a heat supply source. This is the operation method.

[0008] The invention of claim 2 is the method of operating an incinerator according to claim 1, wherein air or combustion exhaust gas having a temperature equal to or higher than room temperature is used as a driving fluid for the ejector.

A third aspect of the present invention is the method for operating an incinerator according to the first aspect, further comprising a burner in place of the driving fluid injection nozzle in the ejector. It is.

[0010] The invention of claim 4 is the invention of claims 1 to 3.
The method for operating an incinerator according to any one of claims 1 to 3, wherein heat generated by combustion is used for heat treatment of the incineration ash.

According to a fifth aspect of the present invention, there is provided an incinerator having a grate, a gas supply pipe having one end connected to an upstream region of the combustion chamber and the other end connected to an upper region of a post-combustion stage grate; An incinerator comprising an ejector provided in the middle of a supply pipe and internally burning a part of unburned gas extracted from an upstream region of the combustion chamber.

[0012]

FIG. 1 is a schematic sectional side view showing an embodiment of a waste incinerator according to the present invention. Although the waste incinerator of this embodiment is a grate-type waste incinerator, the present invention is not limited to a grate-type waste incinerator, but is also applicable to fluidized bed furnaces, gasification furnaces, arc furnaces, and the like. it can.

FIG. 1 is a schematic side sectional view showing an embodiment of a grate type waste incinerator to which the present invention is applied. The grate-type waste incinerator of this embodiment is a fully continuous inclined grate-type two-stage incinerator (hereinafter, referred to as “two-stage incinerator”), but the present invention relates to a waste incinerator having another grate. Can also be applied.

In FIG. 1, a hopper 2 is provided upstream of the combustion chamber 1 (on the left side in FIG. 1) for charging incinerated materials (waste such as municipal waste) 7 into the combustion chamber 1. I have. At the bottom of the combustion chamber 1, a grate 11 for burning the incinerated material 7 while moving it is provided so as to be inclined so as to become lower in a direction away from the hopper 2. This grate 1
1 has two stepped portions, which constitute a dry stage grate 11a, a combustion stage grate 11b, and a post-combustion stage grate 11c in this order from the upstream side of the combustion chamber 1. The grate 11
The shape of is not limited to the illustrated one. For example, a fire grate having a horizontal shape or a structure having no step portion can be similarly used.

Below the grate 11, a hollow block 5a to which supply pipes 4a to 4d for supplying the oxidant 8 are connected.
To d are provided. In addition, the said hollow block 5a-
The number of supply pipes 4a to 4d for supplying d and the oxidizing agent is not limited to those shown in the figure, and is appropriately selected depending on the scale, shape, application, and the like of the incinerator.

A combustion chamber outlet 1a is provided above the combustion chamber on the opposite side (downstream side) of the hopper 2, and a boiler unit (hereinafter referred to as "boiler unit") 3 having gas cooling equipment is connected to the outlet 1a. Has been established.

In the two-flow furnace having the above-described structure, as shown in FIG. 1, the incineration material 7 is charged into the combustion chamber 1 from the hopper 2 and the oxidant 8 is hollowed out from the supply pipes 4a to 4d. It is supplied to the incinerator 7 moving on the grate 11 through the blocks 5a to 5d.

The incineration material 7 introduced into the combustion chamber 1 is dried by the oxidizing agent 8 supplied through the cavity block 5a on the drying stage grate 11a and the flame in the combustion chamber 1 and the radiant heat from the hot wall. At the same time, the temperature is increased to gasify and burn. The incinerated material 7 that has started burning is the combustion stage grate 1
1b, and is burned by the oxidizing agent 8 supplied through the hollow blocks 5b, 5c to form incinerated ash. The unburned ash sent to the post-combustion grate 11c is completely burned by the oxidizing agent 8 supplied through the hollow block 5d. The ash remaining after the combustion is discharged from the incineration ash discharge port 12 to the outside.

As shown in FIG. 1, the supply pipes 4a to 4d for supplying the oxidizing agent 8 to the respective hollow blocks 5a to 5d are provided with:
Flow meters 20a to 20d and regulating valves 21a to 21d are provided so that the flow rate of the oxidizing agent 8 to be supplied can be individually controlled.
Further, there is provided a flow control device 22 for taking in signals from the flow meters 20a to 20d and individually adjusting the opening of each of the adjusting valves 21a to 21d to control the oxidant to a predetermined flow rate.

The combustion gas containing a large amount of unreduced unburned gas such as carbon monoxide and hydrocarbons generated by gasification of the incinerated material on the upstream side in the combustion chamber 1, for example, on the dry stage grate 11a is It rises inside the combustion chamber 1 and proceeds to the outlet 1 a along the ceiling of the combustion chamber 1. Further, the combustion gas generated from the incineration material on the downstream side in the combustion chamber 1 rises in the combustion chamber 1 and the combustion gas in the combustion chamber 1 in the opposite direction to the combustion gas generated from the upstream side in the combustion chamber 1.
To the exit 1a along the ceiling. The combustion gas from the upstream side and the combustion gas from the downstream side are mixed and agitated in the stagnation space near the combustion chamber outlet 1a, and reburned.

Further, the exhaust gas after the re-combustion flows into the boiler section 3 connected to the downstream side of the outlet 1a, is heat-exchanged and cooled, and is then discharged to the outside via an exhaust gas treatment facility or the like. .

It should be noted that the invention according to the present embodiment employs a combustion chamber 1
Needless to say, the present invention can be similarly applied to an incinerator provided with an intermediate ceiling. In this case, the combustion gas on the upstream side and the combustion gas on the downstream side in the combustion chamber 1 are once separated by the intermediate ceiling provided near the outlet 1a in the combustion chamber 1 and then stay in the stagnation space near the combustion chamber outlet 1a. It is re-merged, whereby the mixing and stirring in the staying space are further promoted, and the re-combustion is effectively performed.

In the waste incinerator as described above, the operating method of the incinerator according to the embodiment of the present invention is such that a part of the unburned gas in the combustion chamber extracted by the ejector is burned in the ejector, Is used as a heat supply source.

Here, as the unburned gas in the combustion chamber, in the case of the incinerator shown in FIG. 1, it is preferable to use the gas in the upstream region in the combustion chamber 1. The gas in the upstream region in the combustion chamber 1, for example, the gas in the upper region of the dry stage grate 11 a contains a large amount of reducing unburned gas such as carbon monoxide and hydrocarbon generated by gasification of the incineration material. Because there is.

FIG. 2 is a configuration diagram showing an example of the ejector used in the present embodiment. As shown in FIG.
Has a driving fluid ejection nozzle 32, a mixing chamber 33, and a diffuser section 34. When the driving fluid is jetted out of the driving fluid injection nozzle 32 as a jet, the mixing chamber has a negative pressure, and the unburned gas in the combustion chamber is sucked by the viscosity of the driving fluid and the driving pressure. In the mixing chamber in the ejector 31, the driving fluid and the sucked unburned gas in the combustion chamber are mixed and burned. Then, the heat generated by the combustion is used as a heat supply source. Note that an ignition source such as a pilot burner may be provided in the ejector 31 to ensure that the sucked unburned gas ignites and burns in the ejector. It is also preferable that the wall of the ejector has a water-cooled jacket structure in order to reduce the influence of the heat of combustion.

The performance of the ejector is determined by the shape and dimensions of each part of the diffuser and the throat area ratio (the ratio of the cross-sectional area of the driving fluid jet nozzle to the mixing chamber cross-sectional area), and the flow rate of the driving fluid and the driving fluid jet nozzle The suction flow rate of the unburned gas in the combustion chamber and the like can be controlled by the position and the like.

By extracting the unburned gas in the combustion chamber using the ejector 31, the unburned gas can be drawn into the mixing chamber in the ejector 31 at a high temperature without using a blower.

Here, the heat generated by the combustion in the ejector can be used, for example, as a heat supply source in the heat treatment of incinerated ash. Halogenous substances contained in the incineration ash, for example, harmful substances such as dioxins and heavy metal salts, partially evaporate when the temperature of the incineration ash is set to 250 ° C or higher, and evaporate when the temperature is set to 400 ° C or higher. It has been found that the effect is particularly remarkable. Thus, by setting the temperature of the incinerated ash to 250 ° C. or more, more preferably 400 ° C. or more, harmful substances are released from the incinerated ash, and the incinerated ash can be rendered harmless. Therefore, the incineration ash can be made harmless by heating the incineration ash using the heat generated by the combustion in the ejector as a heat supply source and setting the temperature of the incineration ash to 250 ° C. or more, more preferably 400 ° C. or more.

As the heat treatment of the incinerated ash, for example, when the incinerated ash on the post-combustion stage grate 11c shown in FIG. 1 is heated and heat-treated, the ash treatment provided in the incinerator or provided independently. It can be applied to the case where incineration ash is heated in a furnace.
Further, it can be used as a heat supply source for reheating exhaust gas when the exhaust gas from the incinerator is reused as an oxidizing agent.

In the incinerator shown in FIG. 1, when the incineration ash on the post-combustion stage grate 11c is heated and heat-treated, for example, the incineration ash on the post-combustion stage grate 11c is directly heated by high-temperature exhaust from the ejector 31. In this case, the outlet of the high-temperature exhaust gas discharged from the ejector 31 is
It is necessary to install the incineration ash on 1c in a position where the exhaust gas directly hits. When the incineration ash on the post-combustion grate 11c is heated by the radiant heat of the high-temperature exhaust gas discharged from the ejector 31, the position where the high-temperature exhaust gas can be discharged to the region above the after-combustion grate 11c is set. It is necessary to install an outlet. The number of the outlets is not particularly limited, and one or more outlets can be provided, and can be appropriately selected depending on the shape of the incinerator.

The above method comprises the steps of: a gas supply pipe 30 having one end connected to an upstream area in the combustion chamber 1 and the other end connected to an area above the post-combustion grate 11c;
And an ejector 31 provided in the middle of the combustion chamber 1 and burning the unburned gas extracted from the upstream area in the combustion chamber 1 therein. Here, the gas supply pipe 3
0 is connected at one end to a gas outlet 26 provided on the furnace wall or the furnace ceiling in the upstream region in the combustion chamber 1 and the other end is connected to the furnace wall or the furnace ceiling in the region above the post-combustion grate 11c. It is connected to a gas supply port 25 provided. A part of the unburned gas in the upstream region in the combustion chamber 1 extracted from the gas extraction port 26 is burned in the ejector 31, and the high-temperature exhaust gas generated by the combustion is post-combusted from the gas supply port 25. The incineration ash on the post-combustion stage grate 11c is heated and rendered harmless by supplying it to the region above the stage grate 11c.

The gas supply pipe 30 may be provided with a dust remover upstream of the ejector 31. By providing the dust removing device, it is possible to avoid a problem that dust adheres to a driving fluid ejection nozzle or the like provided in the ejector 31 and the nozzle is closed, and a flow rate adjustment when supplying the driving fluid is performed. Controllability of the ejector 3
It is possible to further improve the stabilization of the combustion within 1.

Here, as the driving fluid for the ejector 31, it is preferable to use air or combustion exhaust gas at a temperature higher than room temperature. By using air or combustion exhaust gas at a temperature equal to or higher than room temperature as the drive fluid, the viscosity of the drive fluid increases, and the flow rate ratio of the ejector (the oxidant suction flow rate / drive flow rate) can be increased. The temperature of the driving fluid is preferably 100 ° C. or higher in consideration of the transport efficiency.

Here, as the air having a temperature equal to or higher than the normal temperature, for example, air heated by a heat exchanger or an electric heater using sensible heat of exhaust gas can be used. Further, as the combustion exhaust gas, for example, the combustion exhaust gas discharged from the incinerator after dust has been removed by an exhaust gas treatment facility,
Alternatively, LPG gas and combustion gas by air can be used. Since the temperature of the combustion gas by the LPG gas and the air is as high as about 1400 ° C., the effect of improving the transport efficiency is high and more preferable.

It is preferable to use a gas having a pressure higher than the atmospheric pressure as the driving fluid. This is because the use of a gas having a pressure higher than the atmospheric pressure can increase the driving flow velocity and increase the transport efficiency.

The driving fluid jet nozzle 32 is
It is preferable to use a heat-resistant material, for example, ceramic. This is because high temperature resistance is improved by using ceramic.

Further, a burner can be used in place of the driving fluid ejection nozzle in the ejector 31. This is because the use of the burner makes it possible to reliably ignite and burn the sucked unburned gas.

It is also preferable to spray a gas for purging deposits onto the driving fluid ejection nozzle 32 provided in the ejector 31. By spraying a gas for deposit purging onto the nozzle 32 for driving fluid ejection provided in the ejector 31, dust contained in unburned gas in the combustion chamber can be prevented from adhering to the nozzle. In addition, the problem that the nozzle is blocked by dust can be avoided. Thereby, controllability such as flow rate adjustment when supplying the driving fluid is improved, and it is possible to further improve the stabilization of combustion in the ejector 31.

FIG. 3 is a view showing an ejector 31 provided with a gas purging nozzle 35 for purging an adhering substance for blowing a gas for adhering substance purging. FIG. 3 illustrates a case where two gas spray nozzles 35 for purging the deposits are provided. However, the number and positions of the gas blowing nozzles 35 for purging the deposits are not limited to those illustrated, and the driving fluid The number and the installation position are appropriately selected within a range in which dust can be prevented from adhering to the injection nozzle 32.

Here, the gas supplied into the ejector from the gas purging nozzle 50 for purging the deposits is not particularly limited, but for example, nitrogen or the like can be used. Further, it is preferable to supply these gases while generating a pulsating flow by blowing them in a pulsed form at a high pressure. This is because it has an effect of more effectively preventing the adhesion of dust. It is preferable that the gas supplied from the gas purging nozzle for purging the deposit 35 into the ejector 31 be supplied in a direction that does not hinder the flow of the oxidizing agent to be sucked.

The temperature of the oxidant 8 supplied into the combustion chamber 1 from below the grate 11 can be increased by using heat generated by combustion in the ejector. By increasing the temperature of the oxidizing agent 8, the drying and incineration efficiency of the refuse is improved,
Further, the amount of exhaust gas can be reduced.

Although the embodiments have been described above, the present invention is not limited to the above embodiments, and various modifications can be made in the implementation stage without departing from the scope of the invention. In addition, the embodiments may be implemented in appropriate combinations as much as possible, and in that case, the combined effects can be obtained.

[0043]

As described above, according to the present invention, there is provided an incinerator operating method and an incinerator in which heat generated by burning unburned gas in a combustion chamber can be used for a multipurpose as a heat supply source. Is provided.

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view showing one embodiment of a waste incinerator according to the present invention.

FIG. 2 is a configuration diagram illustrating an example of an ejector used in the first embodiment.

FIG. 3 is a view showing an ejector provided with a gas purging nozzle for purging a deposit, which blows a gas for purging a deposit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion chamber 1a Combustion chamber outlet 2 Hopper 3 Boiler part 3a Boiler part outlet 4a-d Supply pipe 5a-d Cavity block 7 Incineration object 8 Oxidizer 11 Grate 11a Dry stage grate 11b Combustion stage grate 11c Post combustion stage Grate 20a-d Flow meter 21a-d Regulator valve 22 Flow control device 25 Gas outlet 26 Gas supply port 30 Gas supply pipe 31 Ejector 32 Driving fluid injection nozzle 33 Mixing chamber 34 Diffuser section 35 Gas blowing for deposit purging nozzle

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hirohito Ishibashi 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term in Nihon Kokan Co., Ltd. (reference) 3K065 AA01 AA24 AB03 AC01 AC03 BA03 HA01 3K078 AA03 BA03 BA13 CA03 CA07 CA11 CA27

Claims (5)

[Claims] 1. A method for operating an incinerator, characterized in that a part of unburned gas in a combustion chamber extracted by an ejector is burned in the ejector, and heat generated by the combustion is used as a heat supply source. 2. The method for operating an incinerator according to claim 1, wherein air or combustion exhaust gas at a temperature equal to or higher than room temperature is used as a driving fluid for the ejector. 3. The method for operating an incinerator according to claim 1, further comprising a burner in place of the driving fluid injection nozzle in the ejector. 4. The method for operating an incinerator according to claim 1, wherein the heat generated by the combustion is used for heat treatment of the incineration ash. 5. An incinerator having a grate, a gas supply pipe having one end connected to an upstream area of the combustion chamber and the other end connected to an area above the post-combustion grate, and An incinerator provided therein, and an ejector for internally burning a part of the unburned gas extracted from the upstream region of the combustion chamber.