JPH0357367B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to the production of incinerated ash in a powder combustion incinerator that pulverizes and incinerates various industrial wastes, such as waste liquid containing a large amount of organic matter. This invention relates to a method and device for preventing adhesion inside a furnace.

(Prior technology) An incinerator (incinerator) that dehydrates various industrial wastes containing a large amount of organic matter and then pulverizes and dries the material in the form of cakes, blocks, sheets, etc., and then burns the powder. Mainly cyclone structure)
There is.

In this type of powder combustion incinerator, the incinerated ash is semi-melted or melted during the swirling combustion process in the furnace, and when it reaches the surface inside the furnace, it adheres to the surface, and the incinerated ash gradually accumulates on top of it. A phenomenon of growth occurs. In particular, when incinerating materials containing raw materials with a low melting point, in both cyclone-type incinerators and incinerators with other structures, the incinerated ash that adheres to the inner surface of the inverted cone-shaped part will be attached to the slope, so it will be weighed down by its own weight. Therefore, they do not fall easily, and as they accumulate one after another, they become blocks and eventually clog the incinerator.

(Problem to be solved by the invention) Therefore, measures have been taken to automatically control the combustion temperature at each height of the combustion zone in the incinerator to prevent overheating and prevent the incinerated ash from melting. According to this, for example, if temperature control is set to suit a substance with a low melting point, unburned matter will increase, and it will be difficult to understand the interaction between NO _x reduction and the amount of soot and dust due to the increase in unburned matter. In addition, changes in the residual moisture of the input powder and changes in the calorific value appear as fluctuations in the combustion zone, making the control system unstable and causing troubles due to high temperature overheating.

In view of this, the present invention does not rely solely on combustion temperature control to prevent the adhesion of incinerated ash, but instead supplies the combustion ash particles that have been incinerated into the incinerator together with the reducing gas. This method removes adhering deposits, cleans the furnace walls, controls the combustion temperature inside the incinerator using reducing gas, and reduces NO _x at the same time. The purpose of this invention is to provide a method for preventing adhesion inside a furnace and a device for achieving the same.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the purpose of solving the problems described above, the present invention provides a powder combustion incinerator in which incinerated ash grains that have been incinerated in this incinerator are reduced to combustion and temperature control. The reducing gas is mixed into the gas and supplied to the excessively high temperature combustion zone inside the incinerator, and this reducing gas controls the combustion temperature inside the incinerator. A method for preventing incineration ash from adhering to the inside of a powder combustion incinerator, which method comprises removing deposits adhering to the furnace wall;
and a furnace body of a powder combustion incinerator, an exhaust heat recovery boiler that introduces hot gas discharged from this furnace body and recovers heat through heat exchange, and a A reducing gas supply system that supplies at least one reducing gas injection nozzle that opens tangentially to the combustion zone, and an incinerated ash particle extraction section that sorts incinerated ash discharged from the furnace body and extracts incinerated ash particles for cleaning. and an incinerated ash particle supply system that introduces the extracted incinerated ash particles to the reducing gas supply system, and the incinerated ash particles are mixed into the reducing gas flowing through the reducing gas supply system to eliminate excess in the furnace main body. The present invention provides a device for preventing incinerator ash from adhering to the inside of a powder combustion incinerator, which is characterized by injecting ash from a tangential direction into a high-temperature combustion zone.

(Function) Reducing gas containing incinerated ash particles is blown out into the excessively high temperature combustion zone of the incinerator, thereby lowering the combustion temperature in the excessively high temperature combustion zone, preventing the melting of the incinerated raw materials, and directing them to the inner wall of the incinerator. At the same time as preventing the adhesion _of
At the same time, the incinerated ash particles contained in the reducing gas and blown in remove deposits adhering to the inner wall surface of the furnace.

(Example) Hereinafter, an example of the present invention using a cyclone type incinerator shown in the drawings will be described.

In the figure, reference numeral 1 indicates the cyclone type incinerator body, which, like a normal cyclone, has an inner cylinder 2 made of heat-resistant steel or water-cooled jacket structure in the center that can separate combustion gas and incinerated ash. The inner cylinder 2 is connected to an exhaust gas communication part 3 and a boiler 4 as a heat exchanger for waste heat recovery, and an auxiliary combustion burner 5 that injects fuel at the time of startup is installed on the upper side of the incinerator main body 1. It is provided in the tangential direction. In this auxiliary combustion burner 5, the opening and closing of a fuel supply valve 8 is controlled by a control section 7 based on the temperature measured by a thermometer 6 that measures the temperature inside the incinerator main body 1.

A conveyor 9 having a screw structure for cooling and discharging incinerated ash is disposed at the bottom of the incinerator body 1, and an incinerated ash particle removal section 10 is provided at the end of the conveyor 9.
is provided. This incineration ash particle removal section 10 is
It has a lock valve 11 provided at the end of the discharge conveyor 9 and an incinerated ash sieve 12 provided above the lock valve 11, and the fine incinerated ash sieved by the sieve 12 is discharged. A humidifying paddle mixer 14 that adds moisture to the incinerated ash and mixes it, and a bunker 15 that stores the incinerated ash discharged from this paddle mixer 14 for disposal are provided on the side of the chute 13 where coarse incinerated ash is discharged. On the side of the chute 16, there is a bunker 17 that can store the ash and supply new sand at the start, a screw-type ash removal conveyor 18 located at the bottom of the bunker 17 to carry out the ash, and a lock valve 19 at the end of the conveyor 18.
and a sedimentation separation tank 20 that receives the incinerated ash discharged from the lock valve 19.

A powder supply nozzle 21 is provided on the side wall of the straight body section which is the combustion zone of the incinerator body 1 on the side opposite to the auxiliary combustion burner 5 for injecting powder, which is the material to be incinerated, into the furnace.
is opened in the tangential direction, and this powder supply nozzle 21
A plurality of (four in the illustrated example) reducing gas ejection nozzles 22 ₁ , 22 ₂ , 22 ₃ , 22 ₄ are arranged in a row at predetermined intervals above and below. Furthermore, the inner cylinder 2
A reducing gas ejection nozzle 23 is provided on the side wall of the conical portion of the incinerator body 1 below the lower end thereof, with an elevation angle toward the inside of the lower end of the inner cylinder 2.

Each of the above-mentioned reducing gas ejection nozzles 22 ₁ , 22 ₂ , 22
₃ , 22, ₄ and 23, the incineration ash particle removal section 1
Branch channels 25 ₁ , 25 ₂ , 2 branch from the reducing gas channel 24 connected to the upper part of the settling tank 20 of No.
5 ₃ , 25 ₄ , 26 are connected, and flow control valves 27 ₁ , 27 ₂ , 27 ₃ , 27 ₄ , 28 are connected to these branch channels.
These control valves are operated by valve opening/closing drive units (motors or solenoids, etc.) 29 ₁ , 29 ₂ ,
Opening/closing and opening degree adjustment are performed by driving 29 ₃ , 29 ₄ , and 30 .

The reducing gas blowing nozzles 22 2 , 2 are provided on the side wall facing the reducing gas blowing nozzles _{22 1} to 22 ₄ .
Temperature detectors 31 are installed at intermediate height positions of 2 ₃ , 22 ₄ , and 23 to detect the temperature of the combustion zone within the incinerator body 1.
₁ , 31 ₂ , and 31 ₃ (thermocouples) are respectively arranged, and the temperature detector 31 ₁ is connected to the reducing gas jet nozzle 2.
The drive unit 29 ₂ of the flow control valve 27 ₂ of 2 ₂ , the temperature detector 31 ₂ below, the drive unit 29 ₃ , and the temperature sensor 31
Reference numerals _{3 and} 3 control drive sections ₂₉₄ , respectively, and the ejection of reducing gas is switched or adjusted by driving the drive sections according to the temperature of each combustion zone.

A reducing gas passage 32 connected to the discharge side of the boiler 4 is connected to the opposite side of the upper part of the sedimentation separation tank 20, and a blower 33 is connected in the middle of this reducing gas passage 32. By driving the blower 33, the heat-exchanged gas from the boiler 4 is sucked into the reducing gas injection nozzles 22 ₁ to 2 of the incinerator body 1.
During this _period , relatively small particles of incinerated ash present in the upper part of the sedimentation separation tank 20 are mixed into the reducing gas, and the incinerated ash particles are mixed into the reducing gas and are ejected from the reducing gas jetting nozzles 22 ₁ to 22 .
It is designed to be ejected from 22 ₄ or 23.

The boiler 4 as the heat exchanger for waste heat recovery is
The boiler main body 34 has smoke pipes 35, 35, .
At the bottom of 6 there is a screw structure discharge conveyor 37.
The conveyor 37 is connected to the incinerated ash sifter 12 through a transport path 39 via a lock valve 38 provided at the end of the conveyor 37. The above-mentioned reducing gas flow path 32 is connected to the exhaust port 40 of the sedimentation separation tank 36. In the figure 4
1 is a water tank as a medium for recovering waste heat,
It passes through pipes 42, 43 and around the smoke pipes 35, 35, . . . of the boiler 4 as shown by the arrows, and is heated and recovered.

A dry powder supply device 45 for powdering raw material 44 to be incinerated and supplying the powder to the incinerator 1 is generally known, and one example is shown in the figure.

A pre-treatment machine 48 that lowers the apparent moisture content of the raw material via a lock valve 47 is installed in a raw material input section 46 into which raw material 44 containing high moisture content is input, and a feeder 49 is connected to the discharge port side of this pre-treatment machine 48. A raw material obtained by mixing the raw material and dry powder is supplied into the lower part of the dryer 50.

A pair of crushing blades 5 are installed in the lower part of the dryer 50.
1 and 51 are provided so as to be rotatably driven, and in the vicinity of these crushing vanes 51 and 51, high temperature gas (250 to 450° C.) coming out of the exhaust port 40 of the boiler 4 is blown through an introduction path 52. I'm getting used to it,
The raw material is splashed up by the rotation of the crushing blades 51, 51, and the hot gas blown through the introduction path 52 instantly evaporates moisture, turns it into powder, raises it, and guides it to the solid-gas separation cyclone 53, where it becomes powder and granules. The waste gas is sucked by a fan 55 through a flow path 54 and introduced into a waste gas processing equipment 56. The clean gas is released into the atmosphere, and the powder is sent to a humidifier via a lock valve 57. The waste is transported, added moisture, and then dumped in a non-polluting state. Further, the powder separated by the solid-gas separation cyclone 53 is connected via a branch damper 58 to a combustion air supply path 59 and a herok valve 60, and is sent to the incineration path 1, and then from the powder supply nozzle 21 to the incinerator 1. Powder is being supplied. 61 is a fan for supplying combustion air and transporting powder, and 62 is a communication pipe.

Next, the operation of the above embodiment will be explained.

The powder dried by the dryer 50 is passed from the communication pipe 62 through the combustion air supply path 59 to the fan 61.
As a preparation for transporting the powder by the drive of the powder supply nozzle 21 to the incinerator main body 1, fuel is supplied from the auxiliary combustion burner 5 to raise the temperature inside the incinerator to the ignition start temperature. After the inside of the incinerator main body 1 reaches a predetermined combustion temperature and becomes a natural state, the auxiliary burner 5 is stopped.

When the powder starts to self-combust, the powder gradually descends while swirling inside the incinerator body 1, and the combustion gas is sent to the boiler 4 through the inner cylinder 2, and the smoke pipes 35, 35
Heat exchange is performed with water while reaching the sedimentation separation tank 36 through... Further, the incinerated ash in the incinerator body 1 settles due to the cyclone action and enters the conveyor 9 from the lower part, and after being cooled, it is sent by the conveyor 9 and enters the incinerated ash sifter 12 through the lock valve 11.
Incineration ash below a certain size is collected in chute 13.
It enters the humidifying paddle mixer 14 through the humidifying paddle mixer 14, and from its end it is thrown into the bunker 15 where it is stored and dumped at the appropriate time. Incineration ash larger than a certain size enters a washed ash bunker 17 through a chute 16, and is supplied to a settling tank 20 through an ash removal conveyor 18 and a lock valve 19.

On the other hand, the temperature of the combustion zone in the incinerator body 1 is measured hierarchically by temperature detectors 31 ₁ , 31 ₂ , 31 ₃ , and when an excessively high temperature combustion zone exceeding a predetermined temperature (for example, 1000°C) occurs. opens the corresponding flow rate control valves 27 ₁ to 27 ₄ and blows the reducing gas into the incinerator body 1 through the reducing gas passage 24 using the blower 33 . At this time, the reducing gas flows through the reducing gas channels 32 and 2.
4, the cleaning incineration ash grains that are larger than a certain size and can ride the pressure are mixed into the reducing gas and blown into the incinerator body 1 as a swirling flow. be included.

As a result, the incinerated ash particles are blown along with the reducing gas onto the inner surface of the furnace wall of the high-temperature combustion zone in the incinerator body 1 or the outer peripheral surface of the inner cylinder 2, and the incinerated ash particles adhere to the inner surface of the furnace wall in a molten or semi-molten state. It hits the powder and peels it off, preventing its adhesion and growth. At the same time, the oxygen concentration is low (oxygen amount around 6%)
The combustion temperature is suppressed by injecting reducing gas, which prevents local temperatures within the furnace from increasing and prevents the powder from melting.

This blowing of the reducing gas is carried out through the temperature detectors 31 ₁ to 31.
31 Based on the detection result of ₃ , the corresponding control valve 2
By controlling the opening and closing of 7 ₁ to 27 ₄ , reducing gas is supplied only to the high temperature zone, and the temperature inside the furnace is made uniform.

When molten powder adheres to the inner surface of the inner cylinder 2, the control valve 30 is opened and the reducing gas containing the incinerated ash particles is blown out from the injection nozzle 23, so that the incinerated ash particles are deposited on the inner peripheral surface of the inner cylinder 2. The welding powder is removed, and the removed incinerated ash grains are sent to the boiler 4 through the communication passage 3, so that while passing through the smoke pipes 35, 35... of the boiler 4, the inner periphery of the smoke pipes Surface cleaning is performed.

The incinerated ash particles and separated powder coming out from the lower ends of the smoke pipes 35, 35... enter the sedimentation separation tank 36 at the bottom, where they are sedimented and separated, and then passed through the conveyor 37, lock valve 38, and transport path 39 to become incinerated ash particles. The incinerated ash is sent to the incinerated ash sieve 12 of the extraction section 10, where it is sieved in the same manner as described above, and the large incinerated ash particles are stored again in the sedimentation separation tank 20 for the next cleaning.
The size of the incineration ash grains used for cleaning is as follows:
Preferably, the diameter is around 0.4 m/mφ.

FIG. 2 shows an embodiment in which the inner cylinder 2 in the above embodiment is not used when it is easily corroded by combustion gas, and in this figure, the details of the dry powder supply device 45 are shown. It has been omitted.

In this embodiment, the incinerated ash and exhaust gas discharged from the lower part of the incinerator main body 1 are transported to the outer casing 9 of the conveyor 9.
a, the incinerated ash is sent to the sedimentation separation tank 63 via the lock valve 11 by the screw 9b, and sent to the boiler 4 through the exhaust gas communication furnace 3, where it is separated from the incinerated ash while passing through the outer casing 9a.

After being sedimented and separated in the sedimentation separation tank 36 at the bottom of the boiler 4, it is sent to an exhaust gas treatment device (not shown) by an induced exhaust fan, and a part of it is branched off as a reducing gas from the reducing gas flow path 32 to a blower 33. It is mixed with incinerated ash particles and thrown into the incinerator main body 1.

Even if the incinerator does not have an inner cylinder 2, the molten powder adhering to the inner wall surface of the incinerator body 1 can be removed by mixing the incinerated ash with the reducing gas and supplying it to the incinerator body 1. Also, it is possible to prevent the temperature inside the furnace from becoming partially high. Note that in FIG. 2, parts common to those in FIG. 1 are designated by the same reference numerals, and explanations thereof will be omitted.

In the illustrated embodiment, the case where the incinerator is a cyclone type has been described, but the structure of this incinerator is not limited to the cyclone type.
Of course, the present invention can also be applied to incinerators of other structures. Furthermore, other configurations are not limited to the illustrated embodiments, and other design changes may be made as desired.

〔Effect of the invention〕

As explained above, according to the method for preventing incineration ash from adhering to the inside of the incinerator according to the present invention, reducing gas is supplied to the combustion zone of the incinerator for incinerating powder, and the reducing gas is reduced to the excessively high temperature combustion zone in the incinerator. By blowing in gas, the combustion temperature in the combustion zone is lowered, and at the same time, the incinerated ash particles included in the reducing gas melt the deposits that adhere to the inner surface of the furnace wall due to the high heat in the high-temperature combustion zone. Therefore, by controlling the local high temperature inside the incinerator and making the temperature inside the furnace uniform and preventing the generation of _NO It is possible to prevent clogging of the incinerator and the occurrence of poor combustion.

Further, according to the incineration ash adhesion prevention device of claims 2 and 3, the exhaust gas of the incinerator is used for heat exchange and then sent to the incinerator as reducing gas, so waste heat can be used effectively. The reducing gas prevents the incinerator from becoming excessively high temperature and prevents the phenomenon of powder adhering to the inner surface of the furnace wall due to melting, while also making it possible to remove deposits from the inner surface of the furnace wall (and inner cylinder surface). , combustion efficiency can be further increased.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
The figure is a configuration diagram showing another modification. DESCRIPTION OF SYMBOLS 1...Incinerator body, 2...Inner cylinder, 4...Boiler (heat exchanger), 5...Assistant combustion burner, 10...Incineration ash particle removal section, 12...Incineration ash sieve separator, 20... Sedimentation separation tank, 21...Powder supply nozzle, 21 ₁ to 2
2 ₄ , 23...Reducing gas jet nozzle, 24, 32
... Reducing gas flow path, 31 ₁ to 31 ₃ ... Temperature detector, 35 ... Smoke pipe, 45 ... Powder supply device, 50
……Dryer.

Claims (1)

[Scope of Claims] 1. In a powder combustion incinerator, incinerated ash grains that have been incinerated in this incinerator are mixed into a reducing gas for combustion and temperature control and sent to an excessively high temperature combustion zone within the incinerator body. The reducing gas controls the combustion temperature within the furnace body, and the incinerated ash particles contained in the reducing gas and flowing along the inner surface of the furnace body remove deposits attached to the furnace wall. A method for preventing incineration ash from adhering to the inside of a body combustion incinerator. 2 A furnace body of a powder combustion incinerator, an exhaust heat recovery boiler that introduces hot gas discharged from this furnace body and recovers heat through heat exchange, and a A reducing gas supply system that supplies at least one reducing gas injection nozzle that opens tangentially to the combustion zone, and an incinerated ash particle extraction section that sorts incinerated ash discharged from the furnace body and extracts incinerated ash particles for cleaning. and an incinerated ash particle supply system that introduces the extracted incinerated ash particles to the reducing gas supply system, and the incinerated ash particles are mixed into the reducing gas flowing through the reducing gas supply system to eliminate excess in the furnace main body. A device for preventing incinerator ash from adhering to the inside of a powder combustion incinerator, characterized by injecting ash from a tangential direction into a high-temperature combustion zone. 3. The incinerator body has an inner cylinder for sucking exhaust gas, a blowout nozzle is provided on the side wall of the furnace body below the lower end of the inner cylinder toward the inside of the lower end of the inner cylinder, and a reducing gas supply system is connected to the blowout nozzle. Incineration in the incinerator for powder combustion according to claim 2, characterized in that a branch supply system from the incinerator is connected and the reducing gas containing incinerated ash particles is blown toward the lower part of the inner cylinder through the jet nozzle. Device to prevent ash from sticking inside the furnace.