JP2007198634A - Shaft type waste melting furnace and its operation stopping method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce costs necessary for waste disposal by reducing the requirement of an inactive gas used in stopping an operation in a shaft type waste melting furnace. <P>SOLUTION: In this shaft waste melting furnace 1, a supply pipe 3 of fuel and combustion supporting gas is connected with a furnace body lower portion, and the waste charged from a supply device 2 is thermally decomposed and melted. A branch pipe conduit 10 is formed in a gas flue 4 for the thermal decomposition gas discharged from a furnace body upper portion, and the branched pipe conduit 10 is connected with the furnace body lower portion through a gas pressure-feed means 11 without disposing a gas component adjusting means. In stopping the operation, the combustion supporting gas from the supply pipe 3 is blocked, and the thermal decomposition gas is supplied to the furnace body lower portion. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The claimed invention relates to a shaft-type waste melting furnace that uses an external fuel or the like to thermally decompose and melt waste such as municipal waste.

  FIG. 4 shows an outline of a general shaft-type waste melting furnace described in Non-Patent Document 1 below. The waste introduced into the furnace of the melting furnace 1 ′ by the supply device 2 gradually descends in the furnace due to its own weight, and supplies the high concentration oxygen (or other combustion-supporting gas) and auxiliary fuel. Is dried and thermally decomposed by the high-temperature gas from the tuyere burner 3a installed in As a result, the volatile component of the combustible component in the waste rises as pyrolysis gas, and is discharged from the flue 4 and sent to the recombustion chamber 5 to remove harmful components. On the other hand, the fixed carbon and ash in the combustible part of the garbage remaining in the furnace descend to the lower part of the furnace body, and the fixed carbon undergoes a combustion reaction with the high concentration oxygen supplied from the tuyere burner 3a, and its reaction heat and auxiliary Due to the amount of heat of the fuel, the ash in the waste melts into slag and is continuously discharged from the lowermost part 1x ′ of the furnace body by natural flow. Such a melting furnace can perform from drying to pyrolysis / melting of the waste in an integrated furnace, and can smoothly gasify / melt the waste using high-concentration oxygen. Some shaft-type waste melting furnaces (such as a coke bed-type shaft furnace) are used in which auxiliary fuel is supplied by adding coke or the like from the top of the furnace body.

When the operation of the melting furnace is urgently stopped due to an earthquake or power failure, the waste body and the supply of the high-concentration oxygen and fuel are stopped, and the furnace body is shown from the pipeline 22 ′ (shown by a broken line). Inert gas is forcibly supplied to the bottom. The reason for sending the gas is that if the deposits remaining in the melting furnace at a high temperature are welded and solidified (lithiated) without any gaps, the ventilation path is blocked. If the air is supplied, a gap can be maintained between the accumulations in the furnace, and a ventilation path from the lower part of the furnace body upward is secured, so that the subsequent restart can be performed smoothly. An inert gas such as nitrogen is used as such a gas in order to avoid burning the furnace deposits and generating heat.
"Mixing and melting test of excavated waste in high concentration oxygen blown shaft furnace" Proceedings of the 15th Environmental Engineering Symposium 2005 of the Japan Society of Mechanical Engineers

  Conventionally, in the shaft-type waste melting furnace as described above, it is necessary to separately procure an inert gas (such as nitrogen) supplied to the lower part of the furnace body when the operation of the melting furnace is stopped. Therefore, when waste processing is performed by the melting furnace of the above type, a considerable cost is generated for the inert gas every time the operation is stopped.

  An object of the present invention is to reduce the cost required for waste treatment by reducing the amount of inert gas used in the shaft-type waste melting furnace.

The shaft-type waste melting furnace according to the claim is a shaft-type waste melting furnace for pyrolyzing and melting waste, and a branch pipe is provided in a flue for pyrolysis gas discharged from the upper part of the furnace body, The branched pipe line was connected to the lower part of the furnace body via the gas pressure feeding means without going through the gas component adjusting means, and when the operation was stopped (the moment when the operation of the melting furnace was stopped, It means the time including the time until the accumulated material in the furnace is cooled and solidified), and the combustion-supporting gas (gas that supports combustion. Oxygen, air, or oxygen-enriched air) supplied to the furnace during operation Is provided with a shut-off means (for example, a valve that can be closed).
The gas component adjusting means refers to means for purifying gas or separating some components. The gas pressure feeding means refers to a means for increasing the gas pressure, such as a fan or an ejector using a compressed fluid as an operating source. Further, the connection of the branched pipe line to the lower part of the furnace body includes not only the case where it is directly connected to the lower part of the furnace body but also the case where it is indirectly connected via another pipe or the like.

According to such a shaft-type waste melting furnace, a part of the pyrolysis gas discharged from the upper part of the furnace body is effective when emergency operation is stopped (or normal operation stop) in the event of an earthquake or power failure. It can be used to reduce the cost of waste disposal. This is because the above pyrolysis gas contains almost no residual oxygen, and therefore, when no combustion-supporting gas is supplied, it does not burn and can be used in an inactive state. Therefore, in the shaft type waste melting furnace configured as described above, when the operation is stopped, the combustion-supporting gas is stopped by the shut-off means and the pyrolysis gas is supplied to the lower part of the furnace body from the branch pipe. For example, the pyrolysis gas has the same effect as the above-described inert gas, and helps to secure a ventilation path for restarting. As a result, the necessary amount of inert gas to be separately procured is reduced, and the cost required for waste treatment is reduced.
Since the pipe branching from the pyrolysis gas flue is not provided with a gas component adjustment means, this melting furnace is configured without requiring a special increase in equipment costs, and energy is used for gas component adjustment. There is no consumption. The pyrolysis gas can be used as an inert gas by supplying it to the lower part of the furnace body without adjusting the components.

In the shaft-type waste melting furnace of the invention, an ejector using a compressed fluid as an operating source may be provided as the above-mentioned pressure feeding means. As is well known, an ejector is an ejection means of a type in which a compressed fluid ejected from an internal nozzle as an operation source entrains surrounding fluid (pyrolysis gas) and discharges it from a diffuser.
Since the above-mentioned pyrolysis gas contains unburned components in the gas, when it falls in temperature, it becomes tar and tends to adhere to the flow path. Therefore, as the pressure feeding means, a rotating blade or the like is arranged in the flow path like a fan, and a large amount of tar does not tend to adhere to them, and an ejector is preferable as described above. In the case of an ejector, there are few members that are obstructed by the gas flow in the flow path, so that the amount of tar attached is small, and since there are no moving parts in the flow path, inconvenience due to tar adherence hardly occurs.

And, when a pipe that supplies a non-flammable gas (inert gas that does not burn flammable gas, that is, a low oxygen content ratio of about 12% or less) as the compressed fluid is connected to the ejector, preferable.
Any gas can be used as the compressed fluid, but if a non-flammable gas is used, the pyrolysis gas supplied into the furnace through the ejector is kept inactive, and combustion does not occur even in a high-temperature furnace.

Dust collecting means is provided in a part of the exhaust flue for the pyrolysis gas up to the branch or the branched pipe, and a pipe for introducing the collected material into the melting furnace (the dust collection) is provided. It may also be provided between the means and the melting furnace. As the dust collecting means, a cyclone, a bag filter, an electric dust collector or the like can be used. The melting furnace into which the collected material is introduced is a shaft-type waste melting furnace that performs the above-mentioned processing (waste pyrolysis and melting), and the discharged pyrolysis gas is passed through the dust collecting means. It is not necessarily the melting furnace itself. It is also preferable that the collected matter discharged and collected from the melting furnace whose operation is stopped is put into another melting furnace which is operating in the vicinity.
If such a dust collecting means or the like is used, unburned solids and ash contained in the pyrolysis gas supplied to the lower part of the furnace body are collected, and they are less likely to adhere to the pressure feeding means or the like. At the same time, the amount of auxiliary fuel used is reduced based on the calorific value of the unburned solid when restarting (resuming operation) when the unburned solid is put into the melting furnace as a collection. become. Further, since the ash is put into the furnace, there is an advantage that the slag conversion rate of the melting furnace is improved (that is, the scattered ash can be reduced).

In the branch pipe connected to the lower part of the furnace body, means for injecting water into the pipe line may be provided on the downstream side of the pressure feeding means (that is, between the pressure feeding means and the lower part of the furnace body).
When the operation of the melting furnace is stopped, if water is injected into the pyrolysis gas supply line by the above-mentioned means for injecting water, the inside of the furnace is cooled quickly and a sufficient amount of gas is supplied to the lower part of the furnace body. As a result, it is possible to secure a ventilation path, thereby further reducing the necessary amount of inert gas to be procured separately. The reason why the amount of gas can be increased is that the volume of the gas increases due to vaporization of the injected water. In order to promote vaporization, water is preferably sprayed. Further, if such an injection means is disposed downstream of the pressure feeding means, there is an advantage that tar which is likely to be generated due to a temperature drop of the pyrolysis gas is difficult to adhere to the pressure feeding means.

  The method for shutting down the shaft-type waste melting furnace described in the claims relates to the shutdown of the shaft-type waste melting furnace that thermally decomposes and melts the waste. In a state where the supplied combustion-supporting gas is shut off, the components of the pyrolysis gas discharged from the upper part of the furnace body are adjusted (similar to the above, gas purification and partial component separation are performed). It supplies to the lower part of a furnace body without being characterized.

  According to this operation stop method, the cost of the operation stop can be reduced by effectively utilizing the characteristics of the pyrolysis gas. That is, when the operation of the melting furnace is stopped, a part of the pyrolysis gas is supplied to the lower part of the furnace body in a state where the combustion-supporting gas is shut off, thereby ensuring a ventilation path for facilitating restart. Since this can be done, it is possible to reduce the necessary amount of inert gas to be procured separately. Since the pyrolysis gas is supplied to the lower part of the furnace body without adjusting the components, no special equipment is required and energy is not consumed for adjusting the components.

For supplying a part of the pyrolysis gas to the lower part of the furnace body when the operation is stopped as described above,
-It is preferable that a part of the pyrolysis gas is supplied to the lower part of the furnace body by increasing the pressure by the pressure feeding means in order to realize smooth supply.
Also,
・ As the above-mentioned pumping means, an ejector using a compressed fluid as an operating source is used, and using a non-flammable gas as the compressed fluid supplied to the ejector prevents trouble caused by tar and pyrolysis gas. Is preferable for keeping the inertness.
A dust collecting means is provided in the pyrolysis gas flow path from the upper part of the furnace body to the pressure feeding means, and the pyrolysis gas passed through the apparatus is sent to the pressure feeding means, and the collected material by the apparatus is collected in the melting furnace ( This refers to a shaft-type waste melting furnace that performs the above-mentioned treatment, and the discharged pyrolysis gas is not limited to the melting furnace itself that is passed through the dust collecting means, but may be put into another melting furnace in operation) Good. This is because there is an advantage that the amount of adhering fuel during operation is reduced and the slag conversion rate is improved while the amount of deposits on the pumping means is reduced.

further,
-When the operation is stopped, water (preferably in the form of mist) may be injected into the pyrolysis gas supplied to the lower part of the furnace body. When water is injected, the inside of the furnace can be quickly cooled, and a sufficient amount of gas can be supplied to the lower part of the furnace body to ensure a ventilation path, so that the required amount of inert gas can be further reduced. In addition, it is particularly preferable that the water is jetted downstream of the ejector.

  According to the shaft type waste melting furnace or the operation stop method according to the claims, it is possible to effectively utilize the characteristics of the pyrolysis gas discharged from the upper part of the furnace body, and to reduce the cost required for the operation. That is, when the operation is stopped, a part of the pyrolysis gas is handled in an inactive state, so that the necessary amount of the inert gas used for securing a ventilation path for restarting can be reduced. Furthermore, by selecting the pyrolysis gas pumping means and the compressed fluid used for it appropriately, or by arranging dust collection means and water injection means in the pyrolysis gas path, etc., smoother operation can be achieved and cost can be reduced. It is also possible to proceed with the reduction.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3 showing a shaft type waste melting furnace and a related pipeline system.

First, based on FIG. 1 which is a basic embodiment of the invention, a basic operation situation of the shaft type waste melting furnace 1 will be described as follows.
When waste is put into the furnace of the melting furnace 1 by the supply device 2, the waste gradually descends in the furnace due to its own weight. A tuyere burner 3a is provided at the bottom of the furnace, and high temperature gas is ejected from the high-concentration oxygen and auxiliary fuel supplied from the supply pipe 3, so that the waste is dried and thermally decomposed by the heat. As a result, the volatile component of the combustible component in the waste rises as a pyrolysis gas, and is discharged from the upper part of the furnace body through the flue 4 and sent to the recombustion chamber 5. On the other hand, fixed carbon and ash in the combustible portion of the garbage remain in the furnace, and both descend to the bottom of the furnace body. The fixed carbon undergoes a combustion reaction with the high-concentration oxygen supplied from the tuyere burner 3a, and the ash in the waste is melted by the reaction heat of the fixed carbon and the amount of heat of the auxiliary fuel to become slag. It is output continuously from the bottom 1x.

  In the example of FIG. 1, when the melting furnace 1 urgently stops operation due to an earthquake, a power failure or the like, a part of the pyrolysis gas that comes out of the melting furnace 1 continuously from the operation is removed from the furnace body of the same melting furnace 1. The lower part is supplied as an inert gas. As an equipment configuration, a branch point 4a is provided in the middle of the flue 4 for pyrolysis gas extending from the upper part of the furnace body, and the branch pipe 10 is connected to the lower part of the furnace body. The branch pipe 10 is provided with a pumping means 11 such as a fan (or an ejector) so that the pressure of the pyrolysis gas can be increased and supplied to the lower part of the furnace body, and a connecting part with the lower part of the furnace body is provided. A blowing nozzle 10a is provided. In the portion downstream of the pressure feeding means 11 (the portion indicated by the broken line in the drawing), the pyrolysis gas is allowed to flow only when the melting furnace 1 is stopped. Note that an emergency power supply is used to start the fan of the pressure feeding means 11 in the event of a power failure.

  When the operation of the melting furnace 1 is stopped, a non-flammable gas (for example, nitrogen, water vapor, or the like) is supplied from the pipe line 22 so as to secure a gap (ventilation path) between the accumulations in the melting furnace 1 to facilitate restarting. In general, an inert gas) is supplied from the outside, blown into the lower part of the furnace body from the nozzle 22a at the tip, and forcibly fed upward in the furnace. As described above, the pyrolysis gas supplied from the branch pipe 10 to the lower part of the furnace body when the operation is stopped is used so as to have the same action as that of the non-flammable gas, and the consumption of the non-flammable gas supplied from the outside. Reduce the amount. Since it is necessary to use the pyrolysis gas in an inert state, the supply pipe 3 is shut off by a valve or the like (not shown) when the operation is stopped to prevent the combustion-supporting gas from being sent into the furnace. . However, during operation, if combustion-supporting gas is supplied into the furnace, and when operation is stopped, the combustion-supporting gas is stopped and non-supporting gas (inert gas) is supplied. In any case, it is possible to make use of the illustrated system including the branch pipe 10 by sending the pyrolysis gas from the branch pipe 10 into the furnace.

  FIG. 2 shows an example in which a part of the system of FIG. 1 is modified. That is, the pyrolysis gas supplied from the flue 4 to the lower part of the furnace body is passed through the dust collecting means (the cyclone 13). The cyclone 13 is provided in the flue 4 up to the branch point 4a, and collects unburned solids and ash in the pyrolysis gas. The bottom of the cyclone 13 is connected to the middle of the melting furnace 1 by a pipe line 14, and the collected material is put into the melting furnace 1. In this way, there is an advantage that the degree of adhesion of tar or the like in the inside of the pressure feeding means 11 is reduced. Note that a hopper or the like that can temporarily store the collected matter may be provided in the pipeline 14 for the collected matter.

FIG. 3 shows a further modification of the system of FIG.
One of the modifications is to connect an ejector-type pumping means 12 to the branch pipe 10 for pumping the pyrolysis gas, and to supply a compressed fluid to be injected into the pumping means 12. That is, both the pipe line 23 and the non-flammable gas pipe line 24 are connected to the pressure feeding means 12 via a fluid switching means (valve or the like) 25. In this way, the pyrolysis gas can be smoothly supplied by the pressure-feeding means 12 that is less likely to cause trouble due to tar, and the pyrolysis gas can be appropriately supplied to the lower part of the furnace body both during and when the operation is stopped. Can be supplied. That is, during the operation of the melting furnace 1, the pyrolysis gas is supplied into the furnace together with the combustion-supporting gas for combustion, and when the operation is stopped, the pyrolysis gas is not used for being used in an inactive state. It can be supplied into the furnace together with the combustion-supporting gas.

The second modification in the example of FIG. 3 is that a means 26 for spraying water in the branch pipe 10 is connected to the branch pipe 10 on the downstream side of the pumping means 12. When water is injected into the pyrolysis gas pipe by this means 26, the inside of the furnace can be quickly cooled, and the amount of gas supplied to the lower part of the furnace body can be increased. The required amount of inert gas sent to the path 22 can be greatly reduced.
Also in the example of FIG. 3, the dust collecting means can be used as in the example of FIG.

  Although the example which uses only one waste melting furnace 1 was introduced above, it is also possible to use two or more similar melting furnaces 1 in parallel. In that case, even if the pyrolysis gas generated from a certain melting furnace 1 is supplied to the lower part of the furnace body of another melting furnace 1, the same effect as described above can be obtained.

It is a figure which shows embodiment of invention, and is a schematic diagram which shows the shaft type waste melting furnace 1 and its related pipe line system. It is a figure which shows another form about implementation of invention, and is a schematic diagram which shows the shaft type waste melting furnace 1 and its related pipe line system. It is a figure which shows another form about implementation of invention, and is a schematic diagram which shows the shaft type waste-melting furnace 1 and its related pipeline system. It is a schematic diagram which shows the conventional general shaft type waste melting furnace 1 'and its related pipe line system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft type waste melting furnace 4 Flue (for pyrolysis gas) 10 Branch pipe 11.12 Pressure feeding means 13 Cyclone (dust collection means)

Claims (10)

A shaft-type waste melting furnace for pyrolyzing and melting waste,
The flue for pyrolysis gas discharged from the upper part of the furnace body branches, and the pipe branched from the flue connects to the lower part of the furnace body via the gas pressure feeding means without going through the gas component adjustment means is being done,
In addition, the shaft type waste melting furnace is provided with a shut-off means for stopping the combustion-supporting gas supplied to the furnace during operation when the operation is stopped.   The shaft-type waste melting furnace according to claim 1, wherein an ejector using a compressed fluid as an operating source is provided as the pumping means.   The shaft type waste melting furnace according to claim 2, wherein a pipe for supplying a non-flammable gas as the compressed fluid is connected to the ejector.   Dust collecting means is provided in the part of the exhaust flue for the pyrolysis gas up to the branch or the branched pipe, and a pipe for feeding the collected material into the melting furnace is attached. The shaft-type waste melting furnace according to any one of claims 1 to 3, wherein the shaft-type waste melting furnace is provided.   5. The means for injecting water into the pipe line is provided on the downstream side of the pumping means among the branched pipe lines connected to the lower part of the furnace body. The shaft-type waste melting furnace described in 1. A method for stopping operation of a shaft-type waste melting furnace for pyrolyzing and melting waste,
When the operation was stopped, the combustion support gas that had been supplied to the furnace during operation was shut off, and a part of the pyrolysis gas discharged from the upper part of the furnace body was adjusted without adjusting the components. A method for shutting down a shaft-type waste melting furnace, characterized in that:   The method for shutting down the shaft-type waste melting furnace according to claim 6, wherein a part of the pyrolysis gas is supplied to the lower part of the furnace body by increasing the pressure by a pressure feeding means.   The shaft-type waste according to claim 7, wherein an ejector using a compressed fluid as an operating source is used as the pumping means, and a non-flammable gas is used as the compressed fluid supplied to the ejector. How to shut down the melting furnace.   Dust collecting means is provided in the pyrolysis gas flow path from the upper part of the furnace body to the pressure feeding means, the pyrolysis gas passed through the apparatus is sent to the pressure feeding means, and the collected material by the apparatus is put into the melting furnace. The method for stopping the operation of the shaft type waste melting furnace according to claim 7 or 8. The method for shutting down the shaft-type waste melting furnace according to any one of claims 6 to 9, wherein water is injected into the pyrolysis gas supplied to the lower part of the furnace body.

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