JP5720981B2 - Waste gasification method - Google Patents

Description

The present invention relates to a waste gas treatment method for supplying a waste was generated by gasified partial oxidation and pyrolysis gas is reformed to generate a reformed gas fuel gas or the like.

  In recent years, it has been promoted to use a gas obtained by partially oxidizing and thermally decomposing waste to gasify it as a fuel gas. As such a waste gasification processing apparatus, an apparatus disclosed in Patent Document 1 can be cited.

  The waste compression molding is partially oxidized and pyrolyzed at the lower part of the high-temperature reaction tower to generate pyrolysis gas, and the pyrolysis gas is reformed at the upper part of the high-temperature reaction tower, and reformed gas containing carbon monoxide and hydrogen Is generated and used as fuel gas. The reformed gas extracted from the high-temperature reaction tower is brought into contact with the coolant in the cooling device, and cooled to a temperature suitable for the subsequent gas purification process.

  In the present invention, such a high-temperature reaction tower is called a gasification reforming furnace.

  There is often a situation in which dust accompanying the reformed gas from the gasification reformer adheres to the inner wall of the connecting pipe that connects the gasification reformer and the cooling device and sends the reformed gas to the cooling device. . When dust adheres to and accumulates on the inner wall of the connecting pipe, the pipe line narrows, the pressure loss of the reformed gas in the connecting pipe increases, and the flow of the reformed gas discharged from the gasification reforming furnace is affected. The pressure in the reforming furnace increases. For safety reasons, it is required to keep the pressure in the furnace below a predetermined value. To that end, it is necessary to reduce the amount of gas passing through the connecting pipe. As a result, the operation efficiency of the gasification reforming furnace decreases. Moreover, in order to remove the dust adhering to the inner wall of the connecting pipe, the operation of the gasification reforming furnace must be periodically stopped, so the operating rate is lowered.

  As a countermeasure for preventing dust from adhering to the inner wall of the connecting pipe, Patent Document 2 describes that a heating device that keeps the temperature of the inner wall of the connecting pipe above 1190 ° C. and below 1300 ° C. is described. That is, in Patent Document 2, by maintaining the inner wall temperature of the connecting pipe at a temperature higher than the melting temperature of the dust accompanying the reformed gas from the gasification reforming furnace, the dust is held in a molten state, and the inner surface of the inner wall of the connecting pipe The molten dust is cooled and solidified to prevent adhesion (Patent Document 2, paragraphs [0027], [0028], [0034]).

  Further, Patent Document 3 discloses that by controlling the inner wall temperature of the connecting pipe to be equal to or higher than the melting temperature of dust adhering to the connecting pipe, it is possible to prevent clogging due to deposits in the connecting pipe, It is described that by adding an agent (limestone, slaked lime), the melting temperature of dust can be lowered and the control target temperature of the inner wall temperature of the connecting pipe can be lowered.

JP 2001-205244 A JP 2001-259600 A JP 2005-226027 A

  However, in the method described in Patent Document 2 or Patent Document 3, a mechanism for circulating a high-temperature gas for heating in the connecting pipe wall or an electric heater is provided as a heating device that keeps the inner wall temperature of the connecting pipe at or above the melting temperature of dust. There is a problem that equipment costs and operating costs increase. In addition, in the method described in Patent Document 3, in addition to the problem that the equipment cost and the operating cost increase to keep the inner wall of the connecting pipe above the melting temperature of dust, the problem that the operating cost further increases due to the addition of a melting accelerator. In addition, depending on the properties of the waste, there is a problem that the effect of lowering the melting temperature of dust due to the addition of a melting accelerator is small, and blockage of the connecting pipe cannot be prevented.

The present invention has been made in view of the circumstances as described above, and it is inexpensive to prevent adhesion of dust to the inner wall of the connecting pipe that connects the waste gasification reforming furnace and the cooling device. It is an object of the present invention to provide a waste gasification method that can be performed stably regardless of the properties of the waste.

In the waste gasification method according to the present invention, a gasification reforming furnace for generating a reformed gas by reforming a gas generated by partially oxidizing and thermally decomposing waste and gasifying the gasification reformer. Waste gasification having at least a cooling device that receives and cools the reformed gas from the quality furnace, and a connecting pipe that connects the gasification reforming furnace and the cooling device and sends the reformed gas to the cooling device A processing device is used .

In such a waste gasification method , the present invention blows an oxygen-containing gas from a burner provided in a connecting pipe into the connecting pipe to burn a part of the reformed gas to generate a high-temperature combustion gas, which is heated by the high-temperature combustion gas. When the pressure loss measured by the pressure loss measuring means in the connecting pipe that keeps the surface temperature of the inner wall of the connecting pipe above the melting temperature of dust and measures the pressure loss in the connecting pipe exceeds the allowable value, it is sent to the connecting pipe In addition to reducing the amount of reformed gas, the deposit attached to the inner wall surface of the connecting pipe by the high-temperature combustion gas is heated, melted and fluidized, and flows down to the cooling device to be removed .

  In the present invention configured as described above, a part of the reformed gas is combusted by the oxygen-containing gas blown from the burner, the temperature of the inner wall of the connecting pipe is maintained at or above the melting point of the dust, and the dust is sent to the cooling device. This prevents the molten dust from being cooled and solidified on the inner wall surface of the connecting pipe.

  In the present invention, the burner may inject fuel gas in addition to the oxygen-containing gas. Combustion is promoted by also injecting fuel gas.

In the present invention, the oxygen-containing gas supply amount supplied to the burner is maintained so that the surface temperature of the inner wall of the connecting pipe measured by the temperature measuring means in the connecting pipe for measuring the temperature of the inner wall of the connecting pipe is kept above the melting temperature of the dust. It is preferable to control. Thus, by controlling the temperature, the amount of oxygen-containing gas blown from the burner can be set to an amount that is not excessive and insufficient, and combustion sufficient to maintain the molten state of dust can be performed sufficiently without waste.

In the present invention , when the burner also blows fuel gas, the temperature measuring means for measuring the temperature of the inner wall of the connecting pipe, and the oxygen-containing content supplied to the burner based on the temperature measurement value of the inner wall of the connecting pipe measured by the temperature measuring means A connecting pipe inner wall temperature control means for controlling at least one of the gas supply amount and the fuel gas supply amount may be provided. In this way, by controlling the temperature, the oxygen-containing gas and the fuel gas blown from the burner can be made in an amount that is not excessive and insufficient, and sufficient combustion can be performed without waste to maintain the molten state of the dust. it can.

According to the present invention, part of the reformed gas is combusted in the connecting pipe by blowing oxygen-containing gas or oxygen-containing gas and fuel gas from the burner into the connecting pipe connecting the waste gasification reforming furnace and the cooling device. The high temperature combustion gas is generated, and the inner wall temperature of the connection pipe is maintained at the dust melting point or higher by heating with the high temperature combustion gas. When the pressure loss in the connection pipe exceeds the allowable value, the modification is sent to the connection pipe. In addition to reducing the amount of gaseous gases, the adhering matter adhering to the inner wall surface of the connecting pipe by the high-temperature combustion gas is heated, melted and fluidized, and then flows down to the cooling device to be removed, so that dust adheres to the inner wall of the connecting pipe. Can be easily prevented, and a waste gasification process method can be obtained that can be operated stably at low cost regardless of the properties of the waste.

It is a schematic block diagram which shows the one Embodiment apparatus of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  In FIG. 1, the waste gasification processing apparatus of this embodiment includes a gasification reforming furnace 10 that thermally decomposes and gasifies waste, and a reformation that is generated and reformed in the gasification reforming furnace 10. A cooling device 20 that receives and cools the gas, a connecting pipe 30 that connects the gasification reforming furnace 10 and the cooling device 20 to send the reformed gas to the cooling device 20, and an oxygen-containing gas in the connecting pipe 30 And a control means 50 for controlling the burner device 40 as a preferred embodiment in the present embodiment.

  In the gasification reforming furnace 10, a gas reforming space 12 for gas reforming is formed in an internal space of a vertical furnace body 11, and waste P is placed below the gasification reforming furnace 10. A thermal decomposition unit 13 that deposits and heats the thermal decomposition unit 13 and a melting unit 14 that extends laterally from the thermal decomposition unit 13 are provided. Further, a waste charging portion 15 for charging the waste P from the side is provided on the upper side wall of the thermal decomposition portion 13. The pyrolysis section 13, the melting section 14, and the waste charging section 15 themselves are known from, for example, Patent Document 1 and are not the main subject of the present invention, and thus description thereof is omitted.

  The gasification reforming furnace 10 is provided with an oxygen-containing gas supply port 12A for supplying an oxygen-containing gas for gas reforming to the gas reforming space 12, and is heated by the thermal decomposition unit 13. The gas generated from P and rising is reformed by the oxygen-containing gas and sent to the cooling device 20 as a reformed gas. An oxygen-containing gas supply device 16 is connected to the oxygen-containing gas supply port 12A. A reformed gas delivery port 10A is provided at the top of the gasification reforming furnace 10, and one end side (the left end side in FIG. 1) of the connecting pipe 30 is connected to the reformed gas delivery port 10A. Is connected. A temperature sensor 17 for detecting the temperature of the reformed gas sent from the top of the gasification reforming furnace 10 is provided inside the reformed gas delivery port 10A. It is connected. The control device 18 controls the oxygen-containing gas supply amount to the oxygen-containing gas supply port 12A of the oxygen-containing gas supply device 16 based on the temperature detected by the temperature sensor 17.

  The connecting pipe 30 is disposed with a downward gradient toward the other end side (the right end side in FIG. 1), and is connected to the cooling device 20 at the other end side. A burner 41 of the burner device 40 is provided on one end side of the connecting pipe 30 toward the other end side. An oxygen-containing gas supply device 42 and a fuel gas supply device 43 are connected to the burner 41. The connecting pipe 30 is provided with a temperature sensor 51 for detecting the temperature of the pipe wall as a preferred form, and the temperature sensor 51 is connected to the control device 50. The control device 50 controls the amount of gas supplied to the burner 41 of the oxygen-containing gas supply device 42 and the fuel gas supply device 43 based on the temperature detected by the temperature sensor 51. In the present embodiment, the burner 41 blows out oxygen-containing gas. However, depending on the setting of the control device 50, in addition to the oxygen-containing gas, fuel gas is also blown out as appropriate.

  The cooling device 20 includes a cooling tank 21, and a cooling pipe 22 that connects the other end of the connecting pipe 30 positioned above the cooling tank 21. The cooling pipe 22 hangs down from the other end of the connecting pipe 30 and communicates with the cooling tank 21 at the lower end. A cleaning liquid nozzle 23 for injecting an acidic cleaning liquid into the cooling pipe 22 downward is provided above the cooling pipe 22. Further, a scraping device 24 that scrapes off deposits on the inner surface of the pipe is provided at the upper end position in the cooling pipe 22. The scraping device 24 has a scraping member 24B attached to the lower end of a rod 24A that extends upward to the outside of the pipe. It is designed to scrape off the deposits.

  The cooling tank 21 is provided with a cleaning liquid discharge port 21 </ b> A at the lower portion and a crude gas discharge port 21 </ b> B at the upper portion.

  In the apparatus of this embodiment, gasification and gas reforming by waste partial oxidation / pyrolysis is performed as follows.

  Wastes such as municipal waste and industrial waste accumulated in pits (not shown) are compressed by a press machine (not shown) to form a compression-molded product, and then heated and dry-distilled in a heating furnace (not shown). After that, it is sent to the gasification reforming furnace 10 through the waste charging unit 15 and pyrolyzed by the thermal decomposition unit 13 to be gasified. An oxygen-containing gas is introduced into the furnace from an oxygen-containing gas supply port 12A (lance) provided in the lower part of the gas reforming space 12 of the gasification reforming furnace 10, and this oxygen gas reacts with carbon in the compression molded product. As a result, carbon monoxide and carbon dioxide are generated. In addition, since there is high-temperature steam generated from waste or supplied from the outside, a water gas reaction occurs between carbon and water vapor to generate hydrogen and carbon monoxide. Furthermore, hydrocarbons generated by thermal decomposition and partial oxidation of the compression molded product react with water vapor to generate hydrogen and carbon monoxide. Generating a gas rich in hydrogen and carbon monoxide from the gas generated from these wastes is called reforming, and the reformed gas is discharged from the reformed gas delivery port 10A at the top of the gasification reforming furnace. The Based on the temperature of the reformed gas detected by the temperature sensor 17 provided inside the reformed gas delivery port 10A, the control device 18 contains oxygen to the oxygen-containing gas supply port 12A of the oxygen-containing gas supply device 16. Control gas supply. The reformed gas is sent from the reformed gas delivery port 10A to the cooling device 20 via the connecting pipe 30, and after contacted with the acidic cleaning liquid from the cleaning liquid nozzle 23 by the cooling apparatus 20 and being subjected to rapid acid cleaning, the crude gas is supplied. The gas is discharged from the discharge port 21B, cooled to a temperature suitable for the subsequent gas purification process, and taken out as fuel gas or the like through the gas purification process.

  On the other hand, the pyrolysis residue and ash generated in the lower part of the gasification reforming furnace 10 are melted in the melting part 14, and the melt flows out from the lower part of the gasification reforming furnace to a subsequent homogenization furnace (not shown). In the homogenizing furnace, the metal melt has a large specific gravity and therefore flows under the slag. The melt flows down to the granulation system and is cooled and solidified, and the mixture of granulated metal slag is separated into metal and slag by magnetic separation.

  In such a gas reforming process, the reformed gas extracted from the gas reforming furnace 10 contains dust (ash) generated from waste in the form of molten particles, which is the reformed gas. And flows in the connecting pipe 30.

  In the present embodiment, a burner 41 is provided at one end which is the upstream end of the connecting pipe 30, and oxygen-containing gas (for example, pure oxygen or high-concentration oxygen-containing gas) from the oxygen-containing gas supply device 42 is connected to the connecting pipe 30. It is blown out in the direction of the flow of the reformed gas toward the other end side which is the downstream side of 30. This oxygen-containing gas burns part of the reformed gas in the connecting pipe 30 and retains the surface temperature of the inner wall of the connecting pipe 30 above the melting temperature of dust by the high-temperature combustion gas. Therefore, even if the molten dust in the reformed gas flowing in the connection pipe 30 comes into contact with the inner wall surface of the connection pipe 30, it is not cooled and solidified, and does not adhere to the inner wall surface. The pipe 30 flows to the downstream end together with the reformed gas and is led to the cooling device 20.

  When the reformed gas reaches the cooling pipe 22 of the cooling device 20, the reformed gas comes into contact with the acidic cleaning liquid sprayed from the cleaning liquid nozzle 23 and is cooled, and the dust is solidified and captured by the cleaning liquid and reaches the cooling tank 21. When deposits are generated on the inner surface of the cooling pipe 22, the scraping device 24 is activated to scrape the deposits.

  In the present embodiment, as a preferred embodiment, a temperature sensor 51 for detecting the inner wall surface temperature of the connection pipe 30 is arranged in the connection pipe 30 separately from the above-described temperature control of the reformed gas, and the control is performed based on this detection means. The apparatus 50 controls the gas supply amounts of the oxygen-containing gas supply device 42 and the fuel gas supply device 43. Therefore, in the present embodiment, based on the detected temperature, the oxygen-containing gas supply device 42 is controlled to adjust the oxygen-containing gas supply amount blown from the burner 41 so that the temperature of the inner wall surface of the connecting pipe 30 is melted. Let it be temperature. In this case, the fuel gas may be blown from the burner 41 by operating the fuel gas supply device 43 in addition to the oxygen-containing gas as necessary. Combusting the fuel gas in the connecting pipe 30 means that it is not necessary to burn a part of the reformed gas flowing in the connecting pipe 30, and the amount of combustible gas components in the reformed gas is reduced. However, it is preferable when the reformed gas is finally taken out and used as a fuel gas. The fuel gas supply amount from the burner 41 is adjusted based on the temperature sensor 51 in combination with the oxygen-containing gas supply amount. Thus, the dust is prevented from adhering to the connecting pipe 30.

  When fuel gas is also supplied from the burner 41, an oxygen-containing gas having an oxygen amount smaller than the theoretical oxygen amount necessary for combustion of the fuel gas may be blown from the burner. In this case, the oxygen ratio (supply oxygen amount / theoretical oxygen amount) is preferably 0.7 or more and less than 1.0, and more preferably 0.8 or more and less than 1.0.

  In this way, blowing oxygen-containing gas from the burner into the connecting pipe prevents dust from adhering to the inner wall surface of the connecting pipe. During this time, this deposit accumulates and increases in volume, resulting in a decrease in the effective cross-sectional area in the connecting pipe, resulting in an increase in pressure loss. Therefore, in this case, by providing a pressure loss sensor in the connecting pipe, when the pressure loss exceeds the allowable value, an oxygen-containing gas is blown from the burner, and a part of the reformed gas is burned, Deposits adhering to the inner wall surface of the connecting pipe with the combustion gas can be removed by heating, melting and fluidizing. The removed deposit is sent to the cooling device. In the removal of such deposits, it is also possible to blow fuel gas together with the oxygen-containing gas from the burner into the connecting pipe, as in the case of the dust adhesion prevention described above.

  As described above, when removing the oxygen-containing gas from the burner and, if necessary, the fuel gas into the connecting pipe in order to remove the deposits, in this embodiment, the connecting pipe 30 is directed downward toward the cooling device 20. Since it is inclined and extended, the melt-fluidized deposit easily flows down to the cooling device 20.

  In this way, when performing the operation of melting and fluidizing and removing the deposits adhering to the inner wall of the connecting pipe, the amount of waste supplied to the gasification reforming furnace is reduced, or the gasification reforming furnace It is desired to reduce the amount of reformed gas sent to the connecting pipe by reducing the amount of oxygen-containing gas supplied to the gas and reducing the amount of gas generated in the gasification reforming furnace. By doing so, the deposits are efficiently heated by the high-temperature combustion gas from the burner, and the time for melting and fluidizing and removing the deposits can be shortened.

  Gasification reforming treatment was performed using the waste gasification processing apparatus shown in FIG. When a burner is installed in the upstream part of the connecting pipe and the pressure loss of the connecting pipe becomes higher than the allowable value, the waste supply amount is reduced from 5 t / h to 4 t / h, and then LNG and the theoretical oxygen amount An oxygen-containing gas having a lower oxygen amount is supplied to the burner, LNG is combusted, the inner wall of the connecting pipe is heated to 1300 ° C., which is higher than the melting temperature of the dust, and the deposit adhering to the inner wall surface is melted and fluidized And let it flow down to the cooling device. In 3 hours after supplying LNG to the burner, the deposits were removed, and the pressure loss could be made less than the allowable value. The monitoring of the pressure loss of the connecting pipe and the operation for removing the deposits by the fuel gas from the burner were continued. Since the deposits on the connecting pipe can be removed without changing the temperature of the reformed gas discharged from the gasification reforming furnace at the same 1200 ° C. as in normal operation, the furnace wall of the gasification reforming furnace There was no deterioration of the refractory and the service life of the refractory was not reduced.

Comparative example

  Gasification reforming treatment was performed using a waste gasification processing apparatus in which no burner was provided in the connecting pipe, and the amount of waste supplied was 5 t / h. The temperature of the reformed gas discharged from the gasification reforming furnace was 1200 ° C. When the pressure loss of the connecting pipe becomes higher than the allowable value, the amount of oxygen supplied to the gasification reforming furnace is increased, and the temperature of the reformed gas discharged from the gasification reforming furnace after partially burning the gas in the furnace is set to 1350. The temperature was raised to 0 ° C., the inner wall surface of the connecting pipe was heated, and the attached deposits were melted and fluidized and removed. The monitoring of the pressure loss of such a connecting pipe and the deposit removal operation by the temperature rise of the reformed gas by partial combustion of the gas in the gasification reforming furnace were continued. This deposit removal operation required about 8 hours every 5 days. Since the temperature of the reformed gas is raised to 1350 ° C., deterioration of the furnace wall refractory of the gasification reforming furnace occurs quickly, so that the service life of the refractory is shortened to 1/8 that of normal operation. became.

DESCRIPTION OF SYMBOLS 10 Gasification reformer 20 Cooling device 30 Connecting pipe 41 Burner 50 Connecting pipe inner wall temperature control means (control apparatus)
51 Temperature measuring means (temperature sensor)

Claims (4)

A gasification reforming furnace for generating a reformed gas by reforming gas generated by partial oxidation and thermal decomposition of waste, and a reformed gas containing molten dust from the gasification reforming furnace Waste gasification processing using a waste gasification processing device having at least a cooling device that cools the gasification reforming furnace and the cooling device, and a connecting pipe that sends the reformed gas to the cooling device In the method
An oxygen-containing gas is blown into the connecting pipe from the burner provided in the connecting pipe to burn part of the reformed gas to generate high-temperature combustion gas, and the surface temperature of the inner wall of the connecting pipe exceeds the melting temperature of dust by heating with the high-temperature combustion gas. Hold on
When the pressure loss measured by the pressure loss measuring means in the connecting pipe exceeds the allowable value, the amount of reformed gas sent to the connecting pipe is reduced and the high temperature combustion gas A waste gasification method characterized in that deposits adhering to an inner wall surface are heated, melted and fluidized, and flowed down to a cooling device to be removed . A gasification reforming furnace for generating a reformed gas by reforming gas generated by partial oxidation and thermal decomposition of waste, and a reformed gas containing molten dust from the gasification reforming furnace Waste gasification processing using a waste gasification processing device having at least a cooling device that cools the gasification reforming furnace and the cooling device, and a connecting pipe that sends the reformed gas to the cooling device In the method
At least the fuel gas is burned to generate hot combustion gases, the melting of the surface temperature of the connecting tube wall of the dust by heating by the hot combustion gases seen write blown from the burner provided in connection pipe containing gas and a fuel gas connecting pipe Hold above temperature,
When the pressure loss measured by the pressure loss measuring means in the connecting pipe exceeds the allowable value, the amount of reformed gas sent to the connecting pipe is reduced and the high temperature combustion gas A waste gasification method characterized in that deposits adhering to an inner wall surface are heated, melted and fluidized, and flowed down to a cooling device to be removed . Based on the measured temperature of the inner wall of the connecting pipe measured by the temperature measuring means in the connecting pipe, which measures the temperature of the inner wall of the connecting pipe, the surface temperature of the inner wall of the connecting pipe is maintained above the melting temperature of the dust by heating with high-temperature combustion gas. The waste gasification method according to claim 1, wherein the oxygen-containing gas supply amount supplied to the burner is controlled. Based on the measured temperature of the inner wall of the connecting pipe measured by the temperature measuring means in the connecting pipe, which measures the temperature of the inner wall of the connecting pipe, the surface temperature of the inner wall of the connecting pipe is maintained above the melting temperature of the dust by heating with high-temperature combustion gas. the waste gas treatment method according to claim 2, control at least hand of the oxygen-containing gas supply amount and the fuel gas supply amount supplied to the burner.

Images