JP2005180892A - Structure of waste feeding part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily surely prevent the intrusion of the outside air in a waste feeding part to a furnace in a waste treatment furnace (a furnace particularly including a thermal decomposition process). <P>SOLUTION: A substantially vertical throat part is provided in the waste feeding part to the furnace, and level gauges for detecting the position of the waste in the throat part are provided in two upper and lower stages with a predetermined space within the throat part. A waste feeder is controlled so that supplied waste is regularly present between the upper and lower level gauges during the operation of the furnace. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to the structure of a waste supply section of a solid melting furnace, particularly a waste processing furnace in which a combustible gas is taken out of the furnace including a thermal reaction step such as thermal decomposition of solid waste.

A typical example of a waste supply structure in the upper part of a conventional solid melting furnace is shown in FIGS. In the case of FIG. 2 (a), the solid melting furnace upper supply structure is an open / close structure of two stages of lower dampers (D1) and upper (D2) double dampers attached to the throat part, and the outside air is in the upper hopper. And is intended to prevent flow into the melting furnace.
As another example, as shown in FIG. 2 (b), a screw feeder is used for waste, and in particular, waste is supplied into the furnace while being compressed and transported between the screw and the casing. There is also a structure in which the airtightness is maintained by preventing the outside air from flowing into the furnace. In order to supply waste and maintain airtightness, many systems using a press mechanism instead of the screw are employed.

In any case, improvements were left in the supply of waste in the conventional method into the melting furnace and maintenance of airtightness.
For example, to maintain confidentiality and supply waste with a double damper, waste is supplied to the upper damper by a crane or the like with the upper damper closed, and then there is no waste on the lower damper. In this state, the waste on the upper damper is dropped onto the lower damper while the upper damper is “open”. After confirming that the falling state has ended, the upper damper is returned to the “closed” state, and the waste on the lower damper is dropped and supplied into the melting furnace while the lower damper is opened. Return the lower damper to “closed”. The waste supplied from the hopper by the repetition of this operation is supplied into the melting furnace, but this double damper system always closes one of the upper and lower dampers of the damper device at any time. Therefore, the inflow of outside air into the melting furnace is prevented.
In the case of the screw method, the gap between the screw and the casing is filled with waste by the waste sent by the screw while the gap between the screw and the casing surrounding the screw is narrowed and the waste is supplied with the screw. Has been devised to maintain.
JP 54-68077 A JP-A-5-346217 JP-A-8-121726 JP-A-8-121727 Chemical equipment February 1995 issue “Fused waste incinerator fly ash detoxification recovery system” Life and environment March, 1996 issue "Waste disposal by pyrolysis melting system" Hitachi Zosen Technical Report July 1995 (Vol. 56, No. 2) “Twin torch plasma melting treatment of municipal waste incineration ash” 1994 "Study on Improvement of Direct Melt Processing Technology for Waste (First Report)"

However, the conventional melting furnace waste supply structure has the following problems. Here, a representative example of a double damper system will be described.
In the above method, as described above, the damper is closed because any one of the dampers in the upper stage or the lower stage is intended to ensure airtightness (degree of blockage of ventilation). In this state, the damper and the casing plate surrounding the damper must be in close contact, but it is very difficult to keep the objects on the damper in close contact with each other due to the various physical properties and shapes. Is the reality. For example, if an object on a long string is hanging from the hopper, even if the damper is closed, the damper sandwiches the string-like object, and the damper cannot be reliably closed.
Wet sand and waste are likely to adhere to the periphery of the damper, but when the damper is closed in the same way, the damper is securely attached to form a gap between the damper and the casing. It cannot be closed. Also, when the damper closes, not only can the sealing performance be secured when wood or metal is sandwiched between the damper and the casing, but troubles such as the damper not opening due to their biting often occur. It is. In addition, the impact and static load of the waste always acts on the damper and sometimes it is exposed to the high temperature radiant heat in the furnace. When closed, there is a tendency that even if nothing is bitten, the sealing performance cannot be ensured or smooth opening and closing cannot be performed.

A more difficult problem is that the operation of the melting furnace must be stopped when the damper cannot be opened or closed, or when the seal cannot be secured even when the damper is closed. In addition, a person must enter the throat portion in order to repair the failure.
Naturally, the waste furnace cannot be disposed of during the suspension period due to the suspension of operation of the melting furnace. Therefore, if this period continues for several days or more, it is necessary to pay the cost to the outside to request the disposal of the waste.
In the case of repairing the damper section, the location is often a high place with a poor scaffolding in the upper part of the melting furnace, and dust and soot are attached and accumulated, causing danger of work and sucking harmful substances to the human body during work. It is accompanied by dangers such as.
Furthermore, the damper structure is heavy in order to ensure strength, durability, and airtightness, and the equipment is large and repair and replacement are not easy. Therefore, repair and remodeling costs are high.
In view of the above situation, there has been a demand for an inexpensive structure capable of simple and reliable sealing with a structure that is easy to repair and inspect.
In this state, both the pusher method and the screw method have the same problem of “clogging” in the waste supply section.

In order to solve the above-mentioned problems, the solid melting furnace of the present invention is provided with a relatively long cylindrical throat portion following the hopper in the upper portion of the furnace, and the throat portion has two upper and lower portions with arbitrary intervals. A sensor was attached to the stage. The sensor can detect the presence / absence of waste in the throat portion at the position (height) where the sensor is attached and transmits the signal by detecting the presence / absence of the waste, or the waste based on the signal The supply device can be operated manually or automatically. Of the two upper and lower sensors, the position of the lower sensor attached to the throat part is such that the waste air is moved to the throat part so that outside air is not sucked through the waste supply part (hopper and throat part) during operation of the melting furnace. More than the minimum height filled. In addition, when the upper sensor is installed at the position of the upper sensor and “empty” is detected when there is no waste, the waste feeder is manually or automatically operated based on the “empty” signal of the upper sensor. When the waste is supplied to the throat part through the hopper, the position of the waste in the throat part is not below the position of the lower sensor.
And, the usage method of the upper and lower two-stage sensors provided in the throat part is that the lower sensor sends an “empty” signal to the waste supply operator when the waste in the throat part detects “empty”. In addition, the waste supply operation is performed automatically based on the “empty” signal, and when the upper sensor detects the “charge” in the throat, waste supply operation In other words, a “charge” signal is sent to the employee, or the waste supply is automatically stopped based on the “charge” signal. According to the above structure and operation method, the upper and lower two-stage sensors of the throat section following the hopper are constantly filled with the waste to be treated during the operation of the melting furnace.

The conventional problems can be solved by the structure of the waste supply section of the melting furnace and the operation method thereof.
First, a cylindrical almost vertical throat part is provided at the top of the melting furnace, and two tiers of sensors are installed on the throat part. The position of the lower sensor is the operation of the melting furnace by an operation in which waste is present beyond the lower sensor. Outside air was no longer drawn into the furnace from the hopper. When the surface of the waste in the throat section is lowered from the position of the lower sensor, the lower sensor detects "empty" and sends a waste supply signal to the waste supply operator, so the operator supplies the waste. Or the automatic operation program of the lower sensor and the waste supply device is set up to automatically supply the waste, so that the waste is constantly filled more than the vicinity of the lower sensor. . Without using double dampers or screw conveyors with large structures as in the past, the height of filling of the waste to be treated is kept within a certain range, and the upper and lower stages are attached to the throat part of the waste detection sensor. Since it can be maintained by the waste supply operation using the sensor, the airtightness in the melting furnace can be easily maintained.

Further, the present invention is a method for attaching the two upper and lower sensors to the outer periphery of the throat portion as described above, and detecting the presence / absence of waste in the throat portion by means of ultrasonic waves or the like as in the prior art. Has no structure, so conventional troubles such as entrapment and refilling of waste in the throat section associated with waste supply have been solved. Even if the sensor becomes unstable and needs to be inspected, it can be easily inspected and replaced by removing the sensor outside the throat, so the melting furnace does not have to be stopped for a long time as in the prior art. It was.
In addition, since the airtightness in the melting furnace can be maintained by installing the two-stage sensor with a simple structure as described above at the throat portion, the apparatus cost can be greatly reduced.
In addition, even if the sensor is replaced or repaired due to a trouble in the throat, the work on the corridor outside the melting furnace can be performed, so it is not a conventional work at a high place in the melting furnace. The result was also greatly improved.

One embodiment of the present invention will be described with reference to FIG.
A throat part (3) with a hopper (2) is provided above the furnace ceiling (7) of the solid melting furnace (1), and the throat part (3) can detect the presence of waste in the throat part. S1 and S2 are provided in two upper and lower stages. The lower sensor (S1) is filled with waste to be melted in the throat section (3), and when the melting furnace (1) is in steady operation, no outside air is sucked through the hopper (2) and the throat section (3). When the reference level of the lowest waste is set to S0 among the heights, it is attached at a position above the height (for example, about 1 m) with a margin above it. That is, the height of the lower sensor (S1) is a height at which the throat portion (3) can reliably maintain the airtightness by the supplied waste even if the characteristics, composition, etc. of the waste change over time.
The upper sensor (S2) is positioned above the lower sensor (S1), and when an “empty” state with no waste is detected at the upper sensor position, an “empty” signal from the upper sensor is temporarily output. When the waste is supplied to the throat, the position of the waste in the throat portion is not lower than the lower sensor, but it is simply a volume of at least about 15 minutes of the time average processing capacity of the waste in the melting furnace. Is provided at a position that can be secured between the upper and lower two-stage sensors. Then, the waste supplied by the waste supply device, for example, the crane (8) stays in the throat section (3) for a predetermined time, and then falls by its own weight into the melting furnace. And while falling downward from the position of the furnace ceiling (7), drying (ii) pyrolysis (b), finally pyrolytic carbon in waste at the bottom of the melting furnace, and from the tuyere (10) from the outside The supplied oxygen and, if necessary, supplementary fuel are supplied, and high temperature combustion is performed, and the residue becomes molten slag, which is taken out through Dezawaguchi (6).
The high-temperature combustion gas at this time rises in the melting furnace contrary to the flow of the waste, and the waste falling in the melting furnace is sequentially pyrolyzed and dried, and then becomes a combustible gas containing moisture, It is sucked and discharged from the melting furnace by an induction exhaust fan provided at the rear of the melting furnace (1) from the flue outlet (4).
The combustible gas is controlled at the flue outlet (4) to minus 3 to 5 mmH ₂ O, which is slightly negative from the atmosphere, by adjusting the rotational speed of the induction exhaust fan or the damper opening, but the waste is almost in the throat part. Since control is performed between the lower sensor (S1) and the upper sensor (S2), outside air is prevented from being sucked into the melting furnace through the hopper (2) and the throat part (3).
In other words, a throat portion with a hopper (2) and two upper and lower waste sensors attached to the outside of the throat portion is provided in the upper part of the solid melting furnace (1), and the upper and lower sensors are disposed between the upper and lower sensors. As a result of controlling the position of the waste between the upper sensor and the lower sensor by the sensor signal of the stage, the airtightness in the melting furnace can be easily controlled.
Therefore, it has become possible to easily and reliably prevent the outside air from being sucked into the melting furnace and coming into contact with the combustible gas near the flue outlet (4) between the upper part of the melting furnace and exploding.
In the past, conventional screw feeders, pushers, and two-way compressors that had been struggling to stably maintain the internal pressure of the melting furnace as small as possible to eradicate the prevention of this explosion and ensure stable operation of the melting system. The problems in each system such as a step damper are solved by the present invention with a simple structure.
In addition, the above two-level sensor system is not only applicable to vertical melting furnaces as described above but also to various furnaces in which waste gas is pyrolyzed to generate plastic gas. It can also be applied as a waste supply structure to an incinerator.
As described above, in order to ideally carry out reactions in various furnaces, it is one of the important conditions to prevent the ingress of outside air, and the present invention is a technique that can do so.

  Structure of waste supply part of the present invention   Structure of waste supply section of background technology (a) In case of double damper method (b) In case of screw feeder method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vertical melting furnace 2 Hopper 3 Throat part 4 Flue exit 5 Waste 6 Outlet 7 Furnace ceiling 8 Crane (waste supply apparatus)
9 Slug 10 Tuyere d ₁ Lower tuyere d ₂ Upper tuyere D ₁ Lower damper D ₂ Upper damper S ₀ Reference level S ₁ Lower sensor S ₂ Upper sensor S ₃ Screw feeder

Claims (3)

A waste supply hopper followed by a throat where the waste falls due to gravity is installed in the upper part of the melting furnace. In response to the oxygen-containing gas from the outside and auxiliary fuel if necessary, it burns at a high temperature, and the residue is melted into slag and discharged to the outside, while the high-temperature combustion gas is opposite to the waste flow in the melting furnace. In a solid-type melting furnace with a structure in which wastes are pyrolyzed and dried sequentially while being raised and discharged from the upper part of the melting furnace, the number of sensors that can detect the presence of waste in the throat part is minimized in the throat part. The upper and lower two stages are provided at regular intervals, and the waste to be treated is always filled at least near the position of the sensor on the lower stage to maintain the airtightness in the melting furnace. Of a solid melting furnace characterized by The structure of the Department The throat part is provided below the hopper that supplies waste to the melting furnace by its own weight, and the lower sensor is the position of the lower sensor with respect to the attachment position of the waste detection sensor attached to the throat part with a minimum of two steps above and below. When there is no waste at the position, it is detected that there is no waste, and the supply device operates to supply waste. However, the waste is placed in the melting furnace by the waste before the waste reaches the throat. The position of the upper sensor is adjusted so as not to be lower than the position to maintain the characteristics, that is, the height of the filling of the waste that is not sucked into the melting furnace through the throat during the operation of the melting furnace. When the “empty” state where there is no waste at the position is detected, the waste supply device performs a supply operation based on the “empty” signal of the upper sensor and supplies the waste to the throat through the hopper. Shi Sometimes, already a supply of hardwood type melting furnace according to claim 1, characterized in that the position of the waste throat portion being filled is the position of the above positions in the fall below the position of the lower sensor structure The method for using the waste level detection sensor having a minimum of two upper and lower stages provided with a throat portion for supplying waste and maintaining airtightness in the melting furnace above the solid melting furnace for waste treatment, When the lower sensor detects that there is no waste in the throat, it sends an “empty” signal to the waste supply operator, or automatically uses the waste supply device based on the “empty” signal. When waste is input by operation, and the upper sensor detects "charge" that waste in the throat part is present, it sends a "charge" signal to the above-mentioned operator, or "charge" signal 3. The structure of the supply section of the solid melting furnace according to claim 1 or 2, wherein the operation of charging the waste is stopped by automatic operation of the supply device based on

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