JP4935582B2 - Waste disposal method - Google Patents

Description

  The present invention relates to a solid waste processing method for burning, gasifying, or gasifying and reforming solid waste.

  Currently, there is a shortage of waste disposal sites, and much of industrial waste or general waste is landfilled as it is or after being incinerated and reduced in some form of pretreatment. In many cases, final disposal is performed. There are various methods for the above incineration disposal, but in recent years, management of harmful substances such as dioxin in the gas generated in incineration has become a problem, and it is possible to decompose harmful substances in a high-temperature oxidizing atmosphere. There is a need for a new processing method.

Examples of the waste treatment method capable of such high temperature treatment include waste treatment processes disclosed in Patent Literature 1, Patent Literature 2, and Patent Literature 3.
These are waste treatment processes in which waste is compression-molded and then heated, and the produced compression-molded product is melted and gasified to obtain fuel gas. In this process, first, the waste supplied in a predetermined amount from the waste inlet into the compression device is batch-compressed by the compression device to form a close compression molded product. Next, the compression molded product is pushed into an elongated tunnel type heating furnace (hereinafter referred to as a tunnel type heating furnace) heated from the outside. By repeating this operation, the compression molded product sequentially moves from the charging inlet of the tunnel heating furnace to the outlet. In this way, the moisture evaporates and the surface is carbonized while the compression molded product moves through the tunnel furnace.

  The compression-molded product whose surface is carbonized in the tunnel-type heating furnace is charged into the high-temperature reactor from the high-temperature reactor inlet. An oxygen-containing gas supply pipe is installed at the lower part of the high-temperature reactor. By supplying the oxygen-containing gas into the high-temperature reactor, the combustible component in the compression molded product is burned and pyrolyzed by the oxygen-containing gas. It becomes. When the gas reforming furnace is provided at the upper part of the high temperature reactor, the gasified gas is supplied to the gas reforming furnace directly connected to the upper part of the high temperature reactor, and the incombustible material is melted at the lower part of the high temperature reactor. It becomes a melt composed of molten metal and molten slag and is recovered from the melt outlet at the bottom of the high temperature reactor.

  An oxygen-containing gas supply pipe is installed at the lower part of the gas reforming furnace, and by supplying an oxygen-containing gas into the gas reforming furnace, a part of the pyrolysis gas supplied from the high-temperature reactor is burned, The gas temperature is maintained at 1000 ° C. or higher. The gas discharged from the gas reforming furnace can be recovered as a fuel gas containing carbon monoxide and hydrogen through gas purification steps such as cooling, dedusting, desulfurization, and dehumidification.

  In the case of the waste treatment facility described above, even if a constant amount of oxygen-containing gas is supplied to the lower part of the high-temperature reactor, the gas reforming may occur due to changes in the waste composition or the contact status between the supplied oxygen-containing gas and the compression molded product. The amount and composition of pyrolysis gas supplied to the quality furnace varies greatly. For example, when the amount of pyrolysis gas generated is small relative to the amount of oxygen supplied to the high-temperature reactor, if a certain amount of oxygen-containing gas is supplied in the gas reforming furnace, the amount of oxygen relative to the pyrolysis gas is Since it becomes excess, there exists a possibility that the combustible gas concentration in gas may fall and oxygen may remain in gas. Since the gas discharged from the gas reforming furnace is cooled in the gas purification process, if oxygen remains in the gas as described above, there is a risk of explosion due to oxygen mixing with the cooled gas. .

In order to avoid this danger, the actual equipment always monitors the combustible gas concentration in the refined gas, and reduces the amount of oxygen-containing gas supplied to the lower part of the high-temperature reactor when the combustible gas concentration falls below the threshold. Measures are taken. However, reducing the amount of oxygen-containing gas supplied to the lower part of the high-temperature reactor leads to a reduction in the amount of waste processing.
In order to avoid this, when the combustible gas concentration in the refined gas falls below the threshold value, the amount of the oxygen-containing gas supplied to the gas reforming furnace is reduced to reduce the combustible gas concentration in the refined gas. It is possible to prevent.

In Patent Document 4, the gas calorie is estimated by measuring the concentration of H ₂ gas, which is a combustible gas in the reformed gas on the gasification melting furnace exit side of the waste, so that the estimated calorie becomes a certain value or more. A method is described in which auxiliary fuel such as LNG is introduced into the melting furnace. However, the measurement of H ₂ gas concentration requires a gas sampling time until the analyzer and the response time of the analyzer itself, resulting in a time delay. However, the change in the combustible gas concentration in the actual facility is very short. and going much shorter than the time required for the measurement of H ₂ gas concentration, control for changing the oxygen-containing gas quantity supplied to the H ₂ gas concentration to the gas reformer to index in practice there is a problem . In addition, since the H ₂ gas concentration is one component constituting the combustible gas, it is difficult to say that the index represents the degree of gas oxidation of the entire combustible gas, and the index is not a whole gas but a partial index. I can say that.

As described above, conventionally, measures have been taken to reduce the amount of oxygen-containing gas supplied to the lower part of the high-temperature reactor due to a decrease in the combustible gas concentration in the refined gas, and it has been impossible to avoid a reduction in the waste treatment amount.
Further, in the above processing equipment, it is necessary to control the accumulation level (stock level) of the charged material such as the waste charged in the high temperature reactor. However, the waste properties may change within a relatively short period of time, and the conventional charge control method that limits the maximum height enables stable operation. There wasn't.

JP-A-6-26626 JP-A-6-79252 JP-A-7-323270 JP 2003-268387 A

  The present invention provides a solid waste treatment facility charging control method capable of achieving stable charging and operation in a solid waste treatment facility in which solid waste is charged batchwise. Objective.

The inventors calculated in advance the theoretical treatment time for one charge from the amount of solid waste for one charge and the oxygen-containing gas supplied to the treatment facility, and after the batch charge, The present invention has been completed by finding that the above-mentioned problem can be solved by not performing the next batch charging during the charging stop time determined by the theoretical processing time for one charging.
That is, the present invention is a charging control method for a solid waste treatment facility as described below.

(1) A charging device for charging solid waste in a batch manner and a stock line level sensor are provided. When the level sensor no longer senses the level, the batch charging is performed, and when the level is sensed, the batch is charged. In a charging control method in a solid waste processing facility for stopping charging, burning, gasifying or gasifying and reforming solid waste using an oxygen-containing gas, the amount of solid waste charged batchwise and The amount of oxygen-containing gas required to treat the unit solid waste amount from the amount of oxygen-containing gas supplied to the treatment facility is obtained, and based on this, the theoretical treatment of the one-time charge charged in a batch is performed. The theoretical processing time is calculated as the charging stop time, and after the batch charging, the next batch charging is not performed during the charging stop time. Input control method.
(2) The charging control method for a solid waste processing facility according to (1), wherein the charging stop time is 80% to 99% of the theoretical processing time for the one charging.
(3) The charging of the solid waste is performed by pressing the solid waste with a compression cylinder, the degassing step of heating the obtained compression molded product, and the heated compression molded product in a batch type. The charging control method for a solid waste treatment facility according to the above (1) and (2), wherein the charging is performed by a charging device that performs a charging step of charging.
(4) Using a compression cylinder with a constant driving pressure, the amount of solid waste to be charged in one batch is determined from the compression molding length obtained from the position information of the compression cylinder and the compression obtained from the cylinder cross-sectional area. The solid waste treatment facility charging control method according to (3) above, wherein the molded product volume is multiplied by the average density of the solid waste.

  According to the method of the present invention, it is possible to prevent fluctuations in operation caused by fluctuations in the amount of waste for one batch charged in an economical manner.

The charging control method of the present invention is a solid waste treatment facility for burning, gasifying or gasifying and reforming solid waste with an oxygen-containing gas, and is a device for charging solid waste batchwise. A solid waste treatment facility comprising an input device and a stock line level sensor, wherein the batch charging is performed when the level sensor detects no level, and the batch charging is stopped when the level is detected. Applicable.
Below, although the case where this invention is applied in the waste treatment facility provided with the gasification reforming furnace is demonstrated, this invention is applicable also to a general incinerator and a gasification melting furnace.

FIG. 1 is a side view of a conventional waste treatment facility. In FIG. 1, 1 is a compressor that pressurizes and compresses waste batchwise (2), 2 is a compression cylinder, 3 is a compression support board, 4 is compressed waste (hereinafter referred to as a compression molded product). 4) is a drying area of the compression molded product, 4b is a thermal decomposition area of the compression molded product, and 4c is a compression molded product. carbonized region, _{4 E} is the entrance of a tunnel type heating furnace 4, the high-temperature reaction furnace 5, 10a, 10i compression molded _{product, 11} i, 11 _n are compression molded product was carbonized (hereinafter referred to as carbide product), 12 Mixture of carbonized product and combustion residue, 13 is an oxygen-containing gas inlet, 15 is a melt, 15H is a melt outlet, 20 is a waste inlet, 21 is a waste inlet lid, and 40 is a tunnel type The carbonized product obtained in the heating furnace 4 into the high temperature reactor 5 Extrusion port (: spout carbide products into the high temperature reaction furnace 5), 50 exhaust gas outlet of the high temperature reaction furnace 5, 50a is a gas outlet of the high temperature reaction furnace 5, f ₁ is the compression-molded product 10a, 10i of The moving direction, f ₂ is the moving direction of the carbonized products 11 _i and 11 _n , f ₃ is the flow direction of the pyrolysis gas generated in the tunnel heating furnace 4, and f ₄ is the oxygen-containing gas into the high-temperature reactor 5. , F ₆ is the moving direction of the compression cylinder 2, f ₇ is the moving direction of the compression support board 3, f ₈ is the rotating direction of the lid 21 of the waste charging port 20, and L _L is the high temperature reaction of the carbonized product. The height of the lower end of the extrusion port 40 into the furnace 5, L _H indicates the height of the gas discharge port 50 a of the high temperature reactor 5.

In the waste treatment facility shown in FIG. 1, first, waste supplied batchwise from the waste inlet 20 is compressed using the compressor 1 to form a tight compression molded product 10a. Next, the compression molded product 10a is pushed into an elongated tunnel heating furnace (: horizontal tunnel heating furnace) 4 heated from the outside. At this time, the moisture contained in the waste is squeezed out in the compression step described above and pushed into the tunnel heating furnace 4 together with the waste.
Cross-sectional shape of the compression molded product 10a has an inner wall section having the same shape of the inlet 4 _E of the tunnel type heating furnace 4, the same size, the compression molded product 10a pushes the compression molded product 10a is in contact with the inner wall of the tunnel type heating furnace 4 It is pushed in while maintaining the state. The compression molding 10i moves while sliding in the tunnel heating furnace 4 each time a new compression molding is sequentially pushed.

The tunnel-type heating furnace 4 is heated from the outside as described above, and the inside is heated to about 600 ° C., and the compression-molded product 10 i is dried, pyrolyzed, carbonized in the process of moving and raising the temperature of the compression-molded product 10 i. To do. The carbonized product 11n and gas components generated by thermal decomposition are charged and blown into the high temperature reactor 5 maintained at 1000 ° C. or higher.
Thereafter, the combustible component in the carbonized product including the mineral component and the metal component is combusted and gasified by the oxygen-containing gas. In this case, by adjusting the amount of oxygen in the oxygen-containing gas, the generated gas can be recovered as a fuel gas containing carbon monoxide and hydrogen. In addition, the residue portion that is not gasified by combustion is melted in the high temperature reactor 5 to become a melt 15 and is recovered from the melt outlet 15H at the bottom of the high temperature reactor 5.

  In order to detect the accumulation level (stock level) of the charged material such as the waste charged in the high temperature reactor 5, a deposition level detecting means is provided. There are two types of level detection means of this type, contact type and non-contact type, but the contact type has a thermal shock and thermal damage at the deposition level detection end due to the high temperature atmosphere in the furnace, and the furnace atmosphere. It is not suitable from the viewpoint of preventing external leakage.

There are four types of detection methods based on non-contact methods, specifically, those using sound waves, those using light, those using radiation (gamma rays, etc.), and those using electric (magnetic) waves. The temperature of the directly connected gas reforming furnace is 1000 ° C or higher, and the pyrolysis gas contains a lot of dust and soot. The ultrasonic level meter is difficult to measure accurately due to dust, soot, etc. in the gas.
Therefore, in the present invention, it is preferable to detect the maximum height by installing a γ-ray or ultrasonic transmission type sensor at the upper end of the waste charging surface.

  By the way, in the conventional charging control that limits the maximum height, waste is charged at a slightly higher waste charging speed than a certain amount of oxygen-containing gas supply in the lower part of the high-temperature reactor. When the waste height reaches the level at which the level meter is installed, the charging is stopped for a while, the level sensor waits for the level to drop, and when the level sensor no longer senses the level, the charging is performed in batches, and then the level This is done by stopping batch loading when it is detected. The waste charging speed in this case is determined by the amount of waste charged per time and the number of times of charging per time. The amount of waste fed from the waste hopper into the compactor depends on the size of the compactor and the nature of the waste and is difficult for the operator to control accurately, so It is adjusted by adjusting the number of charges per hour.

However, the properties of the waste may change in a relatively short time, and the amount of waste charged per time fluctuates in a short cycle and sometimes varies greatly every time.
Further, when the oxygen-containing gas is blown and burned and gasified at the lower part of the waste accumulation layer, the waste in front of the oxygen-containing gas blowing nozzle is burned and gasified, and a cavity is formed in front of the nozzle. Normally, the waste deposited directly above this cavity descends and combustion and gasification proceed in sequence, but occasionally or frequently the waste just above the cavity in front of the nozzle forms a bridge, and the waste is May not descend. At the same time, the oxygen-containing gas blows through the waste forming the bridge without burning it, and passes through the upper part of the waste deposition layer. In such a state, since there is no waste in the oxygen-containing gas supply unit, the combustion and gasification of the waste does not occur, or the amount thereof is reduced, and the amount of generated gas from the waste is reduced. When there is such a phenomenon, the system that detects the level of waste and performs the next waste charging does not charge the waste, and the amount of gas generated from the waste is increasingly reduced. To do.

On the other hand, such a bridge also reacts little by little, and sometimes the bridge suddenly collapses, and the level may suddenly drop. At this time, the combustible material is suddenly supplied to the oxygen-containing gas supply unit, and the amount of gas generation increases rapidly. At the same time, it is detected that the level has fallen sharply, and the next batch charging is performed, which promotes a rapid increase in the amount of gas generated. When the oxygen-containing gas blowing part has a large cavity, the level does not recover after one charge, and the gas may be charged without a plurality of intervals.
In this way, a space is created in front of the nozzle, and the amount of gas generated varies greatly due to a decrease in the amount of gas generated when the oxygen-containing gas blows off and subsequent continuous charging of waste.

When charging control is performed to limit the maximum height under such circumstances, the supply rate of waste greatly fluctuates with respect to a certain oxygen-containing gas. It becomes a factor to increase fluctuations such as temperature.
Also, even if batch loading is performed when the level is no longer sensed, if the batched waste is not detected at the level measurement point (for example, if the batch loaded waste rolls around and accumulates) The level meter is not perceived, and during that time, it is often the case that several batch loadings are performed.
Furthermore, since the unloading of the charged material is also irregular in the case of waste, the charging often shows quite irregular charging behavior such as several consecutive times and a long-time stoppage.
If such a thing occurs, in the case of gasification reforming treatment, the amount of gas generated will fluctuate greatly and stable supply of gas will not be possible. Even if the incinerator is a simple gasification furnace, unsatisfactory charging is a serious problem from the viewpoint of maintaining operational stability.

Therefore, in the present invention, in order to avoid the above situation, the theoretical treatment time for one charge is determined in advance from the amount of solid waste for one charge and the amount of oxygen-containing gas supplied to the treatment facility. The batch charge was calculated so that the next batch charge was not performed during the charging stop time determined by the theoretical processing time for the first charge.
In order to set the charging stop time, the oxygen content necessary for processing the unit solid waste amount is determined in advance from the past operation results. This can be determined by dividing the amount of oxygen-containing gas in the same period by the amount of solid waste treated in a certain period (t). This is designated as oxygen-containing gas intensity S (Nm ³ / t-solid waste).
Then, if the amount of solid waste for one batch is M (t), and the supply amount of the oxygen-containing gas at this time is F (Nm ³ / s), one theoretical processing time T (s) Can be represented by the following formula (1).
T (s) = S × M / F (1)

In the present invention, the above theoretical processing time T (s) is set as the charging stop time, and the solid waste is not charged during this time.
By doing in this way, since waste is not continuously supplied at the time of the rapid increase of the gas generation amount, the fluctuation of the gas generation amount can be greatly reduced.

The charging stop time is preferably 80% to 99% of the theoretical processing time for the one charging.
If the level is 80% or less, the level rises quickly, and waste is detected at the level sensor position frequently, and uniform waste supply for each theoretical treatment time corresponding to the waste that is charged at one time. Not. On the other hand, at 99% or more, when the quality of the waste changes, the amount of oxygen necessary for processing the unit waste amount obtained in the past operation is particularly suitable for processing the unit amount of waste at that time. When the amount of oxygen is larger than the required amount of oxygen, the amount of waste retained in the furnace decreases, and the amount of gas generated often decreases.

The solid waste is charged by pressing the solid waste with a compression cylinder, degassing the heated compression molding, and charging the heated compression molding batchwise. It is preferable to be carried out by a charging device comprising the steps.
If the waste is compressed in the pressing process, it has the effect of less scattering of the waste after being charged into the furnace, and the pressure inside the furnace is high because the charging path is blocked by the compression molding. There is an effect that flammable high temperature gas does not leak to the outside.
In addition, since the stroke of the press machine during compression varies depending on the amount of dust for one time, it is preferable to compress the waste at the same pressure while keeping the driving pressure of the press machine constant.

The amount of solid waste for one batch in the above formula (1) is calculated based on the compression molding length obtained from the position information of the compression cylinder at the constant driving pressure and the compression molding volume obtained from the cylinder cross-sectional area. It can be a value multiplied by the average density of solid waste.
If it does as mentioned above, since the positional information on a compression cylinder can be calculated | required easily, an installation can be simplified compared with the case where a batch charging amount is measured directly.
In addition, when directly measuring the amount of waste supplied, it is measured with a waste weight measuring device installed in the crane when it is put into the waste hopper from the waste pit, but a large-scale measuring device is required. Therefore, it is not realistic for economic reasons.

Since the compression rate changes depending on the amount of waste supplied to the cylinder part and the change in the waste quality, the compression molding length obtained from the position information of the compression cylinder also changes. In addition, the average density of solid waste can be obtained by dividing the amount of waste measured by a measuring instrument installed in a crane or the like for a certain period by the total volume of compressed material for the same period. .
In the apparatus of FIG. 1, solid waste is charged from the side of the furnace, but the solid waste can be charged from the top of the furnace.

Examples of the present invention will be described below.
The apparatus used is a solid waste treatment facility shown in FIG. 1 for burning, gasifying or reforming solid waste with an oxygen-containing gas, and charging the solid waste batchwise. A solid waste treatment facility comprising a charging device and a stock line level sensor, wherein the batch charging is performed when the level sensor detects no level, and the batch charging is stopped when the level is detected It is.
FIG. 2 shows an operation pattern of a comparative example in which operation is performed by a conventional method not using the present invention, and FIG. 3 shows an operation pattern of an embodiment in which operation is performed using the present invention. The figure shows the charging timing of waste, whether the level sensor signal sensed or not sensed the waste, and the relative value of the amount of exhaust gas from the high temperature reactor. Further, in the embodiment of FIG. 3, the solid waste is charged into the furnace through a pressing process and a degassing process, and a compression cylinder with a constant driving pressure is used, and compression molding is obtained from position information of the compression cylinder. A value obtained by multiplying the volume of the compression molded product obtained from the length of the product and the cross-sectional area of the cylinder by the average density of the solid waste was defined as the amount of solid waste charged in one batch. Furthermore, 90% of the theoretical processing time for one batch was defined as the charging stop time.
Compared with the comparative example of FIG. 2, in the embodiment of FIG. 3, the charging timing of the waste is more uniform, the fluctuation range of the exhaust gas from the high temperature reactor is also reduced, and the waste is efficiently and stably treated. It became possible to do.

  According to the method of the present invention, it is possible to treat waste efficiently and stably, which is suitable as a method for treating municipal waste.

It is a figure which shows an example of the waste treatment facility with which the method of this invention is applied. It is a figure which shows the operation pattern in a comparative example. It is a figure which shows the operation pattern in an Example.

Explanation of symbols

1 Waste compressor 2 Compression cylinder 3 Compression support 4 Tunnel heating furnace (: Horizontal tunnel heating furnace)
4a Drying area 4b of compression molding Pyrolysis area 4c of compression molding 4C Carbonization area 4 of compression molding _E inlet 4L of tunnel heating furnace 4U floor of tunnel heating furnace 5U ceiling of tunnel heating furnace 5 High temperature reactor 6 Gas reforming furnace 7 Lower temperature reactor 10a, 10i Compression molded product 11 _i , 11 _n Carbonized compression molded product (: Carbonized product)
12 Carbonized product and combustion residue mixture 13 Oxygen-containing gas inlet 14 Oxygen-containing gas and flammable gas inlet 15 Melt 15H Melt outlet 20 Waste inlet 21 Waste inlet 21 Lid 40 Charging product inlet 50 into the high-temperature reactor Exhaust gas outlet 50a of the high-temperature reactor Gas outlet port of the high-temperature reactor 60 Exhaust gas f ₁ Direction of movement of the compression molding f ₂ Direction of movement of the carbonized product f ₃ Flow direction of pyrolysis gas generated in the tunnel-type heating furnace f ₄ Direction of blowing oxygen-containing gas into the high-temperature reactor f ₅ Direction of blowing mixed gas of oxygen-containing gas and combustible gas into the high-temperature reactor f ₆ Moving direction of the compression cylinder f ₇ Moving direction of the compression support plate f ₈ Rotating direction of the lid of the waste charging port L _L Height of the lower end of the extrusion port into the high temperature reactor of the carbonized product

Claims (4)

  It is equipped with a charging device for batch loading solid waste and a stock line level sensor. When the level sensor no longer senses the level, the batch charging is performed. When the level is sensed, the batch charging is performed. In a charging control method in a solid waste treatment facility for stopping, burning, gasifying or gasifying and reforming solid waste using an oxygen-containing gas, the amount of solid waste charged batchwise and the treatment facility The amount of oxygen-containing gas required to process the unit solid waste amount is calculated from the amount of oxygen-containing gas supplied to the tank, and the theoretical processing time for one charge is calculated based on this amount. The charging control method for a solid waste treatment facility, wherein the theoretical processing time is set as a charging stop time, and after the batch charging, the next batch charging is not performed during the charging stop time. .   The charging control method for a solid waste treatment facility according to claim 1, wherein the charging stop time is 80% to 99% of the theoretical processing time for the one charging.   The charging of the solid waste includes a pressing step of compressing the solid waste with a compression cylinder, a degassing step of heating the obtained compression molded product, and a batch of charging the heated compression molded product. The charging control method for a solid waste treatment facility according to claim 1, wherein the charging control is performed by a charging device that performs the charging process.   Using a compression cylinder with a constant driving pressure, the amount of solid waste to be charged in one batch is calculated from the compression molding length obtained from the position information of the compression cylinder and the compression molding volume obtained from the cylinder cross-sectional area. The charging control method for a solid waste treatment facility according to claim 3, wherein the value is obtained by multiplying the average density of the solid waste by an average density of the solid waste.

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