JP6016196B2 - Waste gasification and melting apparatus and waste gasification and melting method - Google Patents

Description

  The present invention is directed to a waste gasification melting furnace in which waste is pyrolyzed in a furnace having a coke bed to melt the residue, and oxygen-enriched air and fuel gas are fed to the waste gasification melting furnace. The present invention relates to a waste gasification and melting apparatus and a waste gasification and melting method to be blown from a tuyere provided in a furnace body.

  As a technology for treating waste such as municipal waste and shredder dust, waste melting treatment is known in which waste is pyrolyzed and burned to melt the pyrolysis residue into slag and discharge it.

  This treatment method can recover the heat of combustion by pyrolyzing and gasifying waste, and it should be disposed of in landfills after melting the pyrolysis residue and discharging it as slag. It has the advantage that the volume can be reduced. There are several methods for such melting treatment, and one of them is a method using a shaft furnace type waste gasification melting furnace having a vertical shape.

  This shaft furnace type waste gasification melting furnace, for example, burns coke deposited in the lower part of the furnace, throws the waste on this high temperature coke, pyrolyzes and partially oxidizes it, and gasifies it as residue Is a furnace that performs a process of melting slag into slag (see Patent Document 1).

  In the shaft furnace type waste gasification and melting furnace of Patent Document 1, the functions of a vertical cylindrical furnace body are roughly divided into three regions in the vertical (up and down) direction. That is, a high-temperature combustion zone having a coke bed with coke deposited at the lower part of the furnace is formed, a waste layer is formed on the high-temperature combustion zone, and a large space above the waste layer at the upper part of the furnace body. The free board part is made.

  In such a gasification melting furnace, oxygen-containing gas is blown into the furnace in each of the three regions. A main tuyere is provided in the high-temperature combustion zone at the bottom of the furnace, and oxygen is enriched to obtain a melting heat source that burns the coke of the coke bed deposited and deposited to melt the pyrolysis residue of waste Air is blown. In addition, the waste layer is provided with a sub tuyere, and air is blown in order to gently flow the waste deposited and deposited, and to thermally decompose and partially oxidize the waste. In addition, the free board part is provided with a third stage tuyere to partially burn part of the pyrolysis gas (combustible gas) generated by pyrolyzing waste and maintaining the inside at a predetermined temperature Air is blown.

  As described above, the shaft furnace type waste gasification and melting furnace is a facility capable of performing both pyrolysis gasification treatment and melting treatment in one furnace as the waste falls in the furnace. The input waste is pyrolyzed to produce gas and residue. The coke in the coke floor is combusted by blowing oxygen-enriched air from the main tuyere to form a high-temperature combustion zone, and the pyrolysis residue of the waste is melted and discharged as slag and metal. The coke floor is a gap created between cokes, and it functions as a high-temperature grate that allows oxygen-enriched air from the main tuyere and high-temperature gas generated by coke combustion to flow, and also allows molten slag and metal to flow. ing. The high-temperature gas generated by coke combustion in the high-temperature combustion zone heats the waste in the waste layer formed on the high-temperature combustion zone, and the waste is thermally decomposed by blowing air from the sub tuyere. The gas containing the combustible gas generated by the gas rises in the waste layer, and is discharged to the secondary combustion chamber outside the furnace from the exhaust flue provided in the upper part of the furnace through the free board part. The gas contains a large amount of combustible gas and is combusted in the secondary combustion chamber, and heat is recovered by the boiler to generate steam, which is used for power generation and the like. Exhaust gas treatment, such as removing relatively coarse dust with a cyclone, cooling with a temperature reducing device, removing harmful gas by reaction with a hazardous substance remover, and removing dust with a dust collector And then released from the chimney to the atmosphere.

  In such a waste gasification and melting furnace, a coke bed in which coke is deposited at the bottom of the furnace is formed, and the coke burns to become a heat source for melting pyrolysis residues. Recently, coke derived from fossil fuels has been used. There is a demand to reduce the amount of carbon dioxide emissions by reducing the amount.

  Therefore, it has been studied to use fuel gas such as LNG, LPG, and combustible gas generated by thermal decomposition in a waste gasification and melting furnace as a substitute for a part of coke. It has been proposed to blow fuel gas together with oxygen-enriched air from (blower tuyere).

  In Patent Document 2, the tip (opening) of the main tuyere (blower tuyere) that feeds oxygen-enriched air into the furnace enters the furnace and enters the coke floor to be positioned. A main tuyere is provided. The fuel gas is supplied into the main tuyere at the tip of the tuyere, blown out from the tip of the main tuyere together with oxygen-enriched air and burned, and the combustion heat of the fuel gas is a source of melting heat in the coke bed. Used as a part.

JP 09-060830 A JP 2001-090923 A

  In order to reduce carbon dioxide emissions, even if fuel gas is blown in as a substitute for a part of coke as in Patent Document 2 in order to reduce the amount of coke used in a waste gasification and melting furnace, the following problems occur: There is. That is, in Patent Document 2, the tip of the main tuyere from which the fuel gas and oxygen-enriched air are blown is located in the coke floor and faces the coke deposit layer, so that the airflow resistance due to the coke grains is large. Therefore, since the flow rate of the oxygen-enriched air blown from the main tuyere is reduced, the amount of oxygen necessary for the combustion of the fuel gas is insufficient, resulting in a problem that the combustion rate of the fuel gas is reduced. .

  In view of such circumstances, the present invention provides a waste gasification and melting apparatus and waste gas that can prevent a reduction in the combustion rate of fuel gas even if the flow rate of the oxygen-enriched air blown into the coke floor is reduced. It is an object to provide a chemical melting method.

  According to the present invention, the above-described problems are solved by configuring the waste gasification and melting apparatus and the waste gasification and melting method as follows.

<Waste gasification and melting equipment>
The waste gasification and melting apparatus according to the present invention, oxygen-enriched air and fuel gas are supplied to a coke bed of a waste gasification and melting furnace that thermally decomposes waste and melts residue in a furnace having a coke bed. The waste gasification melting furnace is blown from the tuyere provided in the furnace body.

  In such a waste gasification and melting apparatus, in the present invention, the tuyere is provided at a plurality of positions in the circumferential direction of the furnace body, and is provided for each tuyere so as to blow and supply oxygen-enriched air to the tuyere. The oxygen-enriched air supply device, the fuel gas supply device provided for each tuyere to feed the fuel gas to the plurality of tuyere, and the respective fuel gas supply devices are controlled independently The oxygen-enriched air supply device at each tuyere has a flow meter for measuring the amount of oxygen-enriched air blown into each tuyere, and the control device is provided at each tuyere. Fuel gas supply at the corresponding tuyere according to the measured value with the flow meter of the oxygen-enriched air supply device at each tuyere so that the ratio of the oxygen-enriched air blowing rate and the fuel gas feed rate is within a predetermined range It is characterized by controlling the amount of fuel gas supplied from the apparatus.

  In the present invention, the control device controls the fuel gas supply amount from the fuel gas supply device at the corresponding tuyere according to the measured value of the flow meter of the oxygen-enriched air supply device at each tuyere, thereby The ratio of the amount of oxygen-enriched air blown at the mouth and the amount of fuel gas supplied is within a predetermined range. Therefore, by setting the predetermined range so as to ensure a sufficient combustion rate of the fuel gas, even if the flow rate of the oxygen-enriched air blown from each tuyere is reduced, the combustion of the fuel gas It is possible to reliably prevent the rate from decreasing. In addition, since the control device independently controls the fuel gas supply device corresponding to each tuyere provided at a plurality of positions in the circumferential direction of the furnace body, the degree of decrease in the blowing flow rate of oxygen-enriched air However, even if each tuyere is different, a sufficient combustion rate of the fuel gas can be reliably ensured in each tuyere.

<Waste gasification and melting method>
In the waste gasification melting method according to the present invention, the oxygen-enriched air and the fuel gas are supplied to the coke bed of the waste gasification melting furnace in which the waste is thermally decomposed in the furnace having the coke bed and the residue is melted. The waste gasification melting furnace is blown from the tuyere provided in the furnace body.

  In this waste gasification and melting method, in the present invention, oxygen-enriched air and fuel gas are supplied independently from each other at each tuyere provided at the furnace body at a plurality of positions in the circumferential direction of the furnace body. Measure the amount of oxygen-enriched air blown into the mouth and according to the measured value of the amount of air blown so that the ratio between the amount of oxygen-enriched air blown at each tuyere and the fuel gas supply amount is within a predetermined range. The fuel gas supply amount to the tuyere is controlled.

  As described above, according to the present invention, the control device supplies the oxygen-enriched air at each tuyere so that the ratio of the amount of blown oxygen-enriched air at each tuyere and the fuel gas supply rate is within a predetermined range. Since the fuel gas supply amount from the fuel gas supply device at the corresponding tuyere is controlled according to the measured value with the flow meter of the device, even if the blowing flow rate of the oxygen-enriched air blown from each tuyere decreases, the fuel A reduction in gas combustion rate can be reliably prevented. Further, the control of the fuel gas supply amount by the control device is performed independently for the fuel gas supply devices respectively corresponding to the tuyere provided at a plurality of positions in the circumferential direction of the furnace body. Even if the degree of decrease in the air flow rate of air varies between tuyere, a sufficient combustion rate of fuel gas can be reliably ensured in each tuyere. In addition, fuel gas can be used as a substitute for a part of coke and combustion heat can be efficiently used as a heat source for melting, so the amount of coke used can be reduced and the amount of carbon dioxide emissions can be reduced.

It is a figure which shows schematic structure of the waste gasification melting apparatus as one Embodiment of this invention. It is the schematic which shows the form which controls the supply amount of the fuel gas in each tuyere about the waste gasification-melting apparatus of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the present embodiment, when a mixed gas in which oxygen-enriched air as an oxygen-containing gas and fuel gas are mixed is blown into the coke bed of the shaft furnace type waste gasification and melting furnace, according to the blown amount of oxygen-enriched air. The fuel gas supply amount is controlled, and prior to the description of these features, a schematic configuration of the shaft furnace type waste gasification and melting furnace will be described with reference to FIG.

  A shaft furnace type waste gasification and melting furnace employed in an embodiment of the present invention shown in FIG. 1 includes waste as a processing object and coke as fuel in the upper part of the gasification and melting furnace 1. An inlet 2 for introducing limestone as a slag component adjusting material into the furnace is provided, and a gas outlet 3 for exhausting the gas in the furnace to the outside of the furnace is provided on the upper side. ing. In addition, an outlet 4 for discharging molten slag and molten metal is provided at the bottom of the gasification melting furnace 1.

In the shaft furnace type waste gasification and melting furnace, the internal space of the gasification and melting furnace 1 is roughly divided into three regions in the vertical direction. This is a region having a middle shaft portion II located at the top and a free board portion III formed at the top. Each of these parts I, II, and III is an area having the following functions. That is, the lower shaft portion I forms a coke bed with the deposited coke, and the coke is burned to form a high temperature combustion zone, and the middle shaft portion II is a waste of the waste put on the high temperature combustion zone. A region where the waste of the waste layer formed by deposition is thermally decomposed, the free board part III, is a region where the generated combustible gas is partially combusted.

  Above the waste gasification and melting furnace 1, a supply device (not shown) for supplying waste such as municipal waste, coke, and limestone used as a component adjusting material for slag to be generated is disposed. Waste, coke, and limestone supplied from this supply device are transported by a transport conveyor (not shown) and charged into the furnace through the charging port 2 at the top of the furnace.

  A tuyere for blowing oxygen-containing gas is provided on the furnace wall for each of the lower shaft portion I, the middle shaft portion II, and the freeboard portion III formed in the waste gasification melting furnace 1. That is, the lower shaft portion I is provided with a main tuyere 5 that burns the deposited coke to form a high-temperature combustion zone and blows a gas mixture for melting the pyrolysis residue, and the middle shaft portion II In addition, a sub tuyere 6 is provided to blow in air for causing thermal decomposition and combustion while causing the waste deposited and deposited to partially burn and slowly flow the waste. A three-stage tuyere 7 for blowing air for partially burning the combustible gas generated by pyrolysis and maintaining the inside of the furnace at a predetermined temperature is provided. The main tuyere 5, the sub tuyere 6 and the three-stage tuyere 7 are provided at a plurality of positions in the circumferential direction of the furnace body (see FIG. 2 for the main tuyere 5).

  Each of the plurality of main tuyere 5 is connected to an air supply pipe (not shown) for injecting a mixed gas into the furnace corresponding to each main tuyere 5, and the air supply pipe is oxygen-rich. The converted air supply device 14 and the fuel gas supply device 15 are connected. The oxygen-enriched air supply device 14 supplies oxygen-enriched air as an oxygen-containing gas obtained by mixing oxygen into the air to the air supply pipe, and the fuel gas supply device 15 supplies the fuel gas to the air supply pipe. It comes to supply. In the air pipe, oxygen-enriched air and fuel gas are mixed to form a mixed gas. The air supply tube only needs to have a configuration in which oxygen-enriched air and fuel gas can be mixed in the tube. For example, a single tube, a double tube, a triple tube, or the like can be used.

  Further, the waste gasification and melting apparatus of the present embodiment has a control device 16, and the control device 16 supplies fuel gas from the fuel gas supply device 15 to the main tuyere 5 as will be described later. The amount is controlled in accordance with the amount of oxygen-enriched air blown from the oxygen-enriched air supply device 14 to the main tuyere 5. The control of the fuel gas supply amount is performed independently for the fuel gas supply device 15 provided for each main tuyere 5.

  FIG. 2 is a schematic view showing a form of controlling the supply amount of fuel gas at each main tuyere 5 for the waste gasification and melting apparatus of FIG. In FIG. 2, the signal flow from the blast flow meter 17 described later to the control device 16 is indicated by a thin broken arrow, and the signal flow from the control device 16 to the fuel gas supply amount adjusting device 18 described later is indicated by a thick broken arrow. It is shown. The control device 16 corresponds to each of a plurality of main tuyere 5 (four in the example of FIG. 2), and in FIG. 2, the correspondence between the control device 16 and each main tuyere 5 is the same. It is shown by attaching | subjecting the alphabet of (A-D).

  The oxygen-enriched air supply device 14 (see FIG. 1) provided corresponding to each main tuyere 5 has an air flow meter 17 that measures the amount of oxygen-enriched air sent to the corresponding main tuyere 5. doing. Further, a fuel gas supply device 15 (see FIG. 1) provided corresponding to each main tuyere 5 has a fuel gas supply amount adjusting device 18 for adjusting the fuel gas supply amount to the corresponding main tuyere 5. have. The fuel gas supply amount adjusting device 18 has a flow rate adjusting valve or a damper (not shown) for adjusting the flow rate of the fuel gas to the main tuyere 5. The control device 16 determines the opening of the flow rate adjustment valve or the damper of the fuel gas supply device 15 at the corresponding tuyere according to the measurement value of the air flow meter 17 of the oxygen-enriched air supply device 14 at each main tuyere 5. By adjusting the fuel gas supply amount, the fuel gas supply amount is controlled. Details of the control will be described later.

  As shown in FIG. 1, a secondary combustion chamber 10 is connected to the gas discharge port 3 and combusts a combustible gas generated by pyrolyzing waste. An air blowing port 11 for blowing air for secondary combustion is provided. Further, the secondary combustion chamber 10 is provided with a boiler 12 adjacent to which heat is recovered from the combustion gas obtained by burning the combustible gas in the secondary combustion chamber 10.

  Exhaust gas from the boiler 12 is exhausted through an exhaust pipe 13 and is detoxified through a temperature reducing device, a dust collector, and an exhaust gas treatment device (both not shown) provided on the downstream side. To be released.

  Next, control of the fuel gas supply amount by the control device 16 will be described. In the present embodiment, an allowable predetermined range is set for the ratio between the amount of oxygen-enriched air blown at the main tuyere 5 and the amount of fuel gas supplied to ensure a sufficient combustion rate of the combustion gas. The data about the predetermined range is stored in the control device 16 in advance. In the present embodiment, the “predetermined range” is set as a range in which a sufficient combustion rate of fuel gas can be secured to such an extent that the pyrolysis residue can be sufficiently melted in the coke bed and the molten slag can be smoothly discharged from the furnace. Has been. In addition, the “predetermined range” is, for example, the amount of oxygen-enriched air necessary for measuring the coke bed temperature while changing the fuel gas supply amount and maintaining the coke bed temperature in an appropriate range. And the ratio of the fuel gas supply amount.

  The oxygen-enriched air supply device 14 sends the measured value of the air flow meter 17, that is, the data of the amount of oxygen-enriched air blown to the main tuyere 5 to the control device 16 continuously or periodically. The control device 16 refers to the data about the predetermined range, and calculates the fuel gas supply amount such that the ratio with the blast volume obtained from the oxygen-enriched air supply device 14 falls within the predetermined range. Then, the control device 16 controls the fuel gas supply amount adjusting device 18 of the fuel gas supply device 15 based on the calculated fuel gas supply amount.

  Thus, in this embodiment, the control device 16 allows the oxygen enrichment at each tuyere to be within a predetermined range so that the ratio of the amount of oxygen-enriched air blown at each main tuyere 5 and the amount of fuel gas supply is within a predetermined range. Since the amount of fuel gas supplied from the fuel gas supply device 15 at the corresponding main tuyere 5 is controlled according to the measurement value of the blower flow meter 17 of the conditioned air supply device 14, the ventilation resistance at the coke floor is increased and each main wing is increased. Even if the flow rate of the oxygen-enriched air blown from the port 5 is reduced, it is possible to reliably prevent a reduction in the combustion rate of the fuel gas. Further, the control of the fuel gas supply amount by the control device 16 is performed on the fuel gas supply amount adjusting device 18 of the fuel gas supply device 15 corresponding to each main tuyere 5 provided at a plurality of positions in the circumferential direction of the furnace body. However, even if the degree of decrease in the flow rate of the oxygen-enriched air flow varies depending on the main tuyere 5, the main tuyere 5 ensures a sufficient combustion rate of the fuel gas. It can be secured. In addition, fuel gas can be used as a substitute for a part of coke and combustion heat can be efficiently used as a heat source for melting, so the amount of coke used can be reduced and the amount of carbon dioxide emissions can be reduced.

  In the present embodiment configured as described above, the waste gasification and melting treatment is performed as follows.

  Waste, coke, and limestone from the supply device are respectively introduced into the furnace by a predetermined amount through the inlet 2 provided in the upper portion of the gasification melting furnace 1, and main tuyere 5, sub tuyere 6, and three From the stage tuyere 7, a mixed gas or air is blown into the furnace. In particular, from the main tuyere 5, a mixed gas obtained by mixing oxygen-enriched air supplied from the oxygen-enriched air supply device 14 and fuel gas supplied from the fuel gas supply device 15 is blown into the furnace. It is. Here, the fuel gas supply amount supplied from the fuel gas supply device 15 is adjusted according to the measured value of the blowing amount of the oxygen-enriched air as described above. The waste introduced from the inlet 2 is deposited on the middle shaft part II in the furnace to form a waste layer, and from the high temperature gas and sub tuyere rising from the high temperature combustion zone of the lower shaft part I. It is dried by blown air and then partially burned and pyrolyzed. The combustible gas generated by pyrolysis is partly combusted by the air blown from the three-stage tuyere 7 in the free board part III, and the free board part III is kept in a high-temperature reducing atmosphere of 850 ° C. or higher. A process for decomposing toxic gas and tar content is performed, and a gas containing a combustible gas is sent to a secondary combustion chamber 10 provided outside the furnace and subjected to secondary combustion, and heat is recovered from the combustion gas in a boiler 12. .

  The coke descends to the lower shaft portion I to form a high temperature combustion zone (coke bed). The residue resulting from the thermal decomposition of the waste in the waste layer descends and reaches the coke floor of the lower shaft portion I. Pyrolysis residue (ash content, incombustible material) is heated by the combustion of coke and fuel gas in the coke bed and melts into molten slag and molten metal. The molten slag and molten metal are discharged from the tap 4 and supplied to a water granulating device provided outside the furnace, cooled and solidified, and the cooled and solidified granulated slag and granulated metal are recovered.

  In the present embodiment, only the mixed gas is blown from the main tuyere 5, but instead of this, dust recovered from the secondary combustion chamber 10 and the boiler 12 may be blown together with the mixed gas. When dust is also blown together with the mixed gas in this way, the dust in the mixed gas melts when it reaches the high temperature combustion zone from the main tuyere 5 and from the outlet 4 at the bottom of the furnace together with the molten pyrolysis residue. Extracted. Thus, the volume can be reduced by melting the dust, and the landfill disposal amount can be greatly reduced.

DESCRIPTION OF SYMBOLS 1 Waste gasification melting furnace 5 (Main) tuyere 14 Oxygen-enriched air supply apparatus 15 Fuel gas supply apparatus 16 Control apparatus 17 (Blower) flowmeter

Claims (2)

Oxygen-enriched air and fuel gas are installed in the furnace body of the waste gasification and melting furnace to the coke floor of the waste gasification and melting furnace that thermally decomposes the waste and melts the residue in the furnace body having the coke bed. In the waste gasification and melting device to be blown from the tuyere,
The tuyere is provided at a plurality of positions in the circumferential direction of the furnace body, and an oxygen-enriched air supply device provided for each tuyere to blow and supply oxygen-enriched air to the tuyere, and a fuel gas A fuel gas supply device provided for each tuyere to supply to the plurality of tuyere and a control device for controlling each fuel gas supply device independently; The activated air supply device has a flow meter for measuring the amount of oxygen-enriched air blown to each tuyere, and the control device is configured to control the amount of oxygen-enriched air blown at each tuyere and the amount of fuel gas supplied. Fuel gas supply from the fuel gas supply device at the corresponding tuyere according to the measured value of the amount of oxygen-enriched air blown by the flow meter of the oxygen-enriched air supply device at each tuyere so that the ratio is within a predetermined range Control the quantity,
The coke bed temperature is measured while changing the fuel gas supply rate, and the coke bed temperature is within an appropriate temperature range where the pyrolysis residue is sufficiently melted in the coke bed to form molten slag and the molten slag can be discharged smoothly from the furnace. Therefore, the predetermined range of the ratio of the oxygen-enriched air blowing rate and the fuel gas supplying rate is the appropriate ratio of the oxygen-enriched air blowing rate and the fuel gas supply rate. A waste gasification and melting apparatus set as a range and stored in advance in a control device. Oxygen-enriched air and fuel gas are installed in the furnace body of the waste gasification and melting furnace to the coke floor of the waste gasification and melting furnace that thermally decomposes the waste and melts the residue in the furnace body having the coke bed. In the waste gasification and melting method to be blown from the tuyere,
The oxygen-enriched air and fuel gas are supplied to each tuyere independently from each other at the tuyere provided at the furnace body at a plurality of positions in the circumferential direction of the furnace body, and the oxygen-enriched air is sent to each tuyere. The air volume is measured, and the control device controls the oxygen-enriched air flow rate according to the measured value of the oxygen-enriched air flow rate so that the ratio of the oxygen-enriched air flow rate and the fuel gas supply rate at each tuyere Control the amount of fuel gas supplied to the tuyere ,
The coke bed temperature is measured while changing the fuel gas supply rate, and the coke bed temperature is within an appropriate temperature range where the pyrolysis residue is sufficiently melted in the coke bed to form molten slag and the molten slag can be discharged smoothly from the furnace. By determining the fuel gas supply amount that can be maintained, the predetermined range of the ratio of the oxygen-enriched air blowing amount and the fuel gas supply amount can be set to an appropriate ratio of the oxygen-enriched air blowing amount and the fuel gas supply amount. A waste gasification and melting method, which is set as a range and stored in advance in a control device .

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