JP2515039B2 - Coal fired boiler equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a slag tap type (wet bottom type) combustion furnace, which has a very high combustion temperature and discharges ash content in fuel as molten ash, and uses this molten ash as a raw material for slag. The present invention relates to a coal-fired boiler facility to which a slag cotton manufacturing apparatus for manufacturing cotton is added.

2. Description of the Related Art The method of disposing of ash discharged from a coal-fired boiler is a serious issue, and there is a great social need for effective use. Most of the coal ash emitted from conventional boilers is so-called fly ash, and as its usage, unprocessed materials are used for landfill and soil improvement, and as intermediate processed materials cement raw materials, raw concrete additive materials, roadbed materials, artificial materials. It is used as a lightweight aggregate, etc., and sound absorbing materials and various building materials are being studied as highly processed materials.

On the other hand, the raw material of the currently produced slag cotton is blast furnace slag, silica stone, basalt, andesite, etc. as the main raw material, and if necessary, a component adjusting agent is added and remelted in a melting furnace such as an electric furnace or cupola, A method is used in which the melt is supplied to a cotton maker and is made into fibers by centrifugal force or fluid pressure such as compressed air or steam.

Problems to be Solved by the Invention A coal-fired boiler has a problem of treatment of coal ash with respect to a heavy oil-fired boiler, and in order to use the discharged ash as a highly processed material, it is said that a manufacturing cost required for a firing step or the like is high. There's a problem.

On the other hand, in the production of mineral wool, there are problems that the energy cost for melting the raw materials is great and the amount of carbon dioxide gas discharged during the production is great.

The present invention discharges from a slag tap type combustion furnace that raises the combustion temperature and lowers the melting point of ash by adding lime necessary for in-furnace desulfurization, and causes the ash to flow in a molten state through an extraction hole in the hearth. It is an object of the present invention to provide a coal-fired boiler facility that can solve the above problems all at once by using molten ash as a raw material.

Means for Solving the Problems In order to solve the above problems, the first means of the present invention is
A lime supply nozzle that supplies lime for desulfurization is provided in the combustion chamber of the slag tap type combustion furnace, and a heating weir having a temperature control device for molten ash is provided at the slag extraction outlet formed in the hearth, and the outlet of the heating weir. In the above, there is provided an apparatus for producing slag cotton to which a raw material inlet is connected, and an additive supply nozzle for supplying lime for component adjustment and melting point adjustment to the heating weir.

The second means is, in addition to the first means, provided with a cover body for shielding the heating weir and the slag production device from the outside air, and at the same time between the combustion furnace and the cover body, the combustion gas in the combustion furnace. The gas introduction path for introducing the gas into the cover body is provided.

Furthermore, the third means is, in addition to the first or second means,
The heating weir is provided with an additive supply nozzle for adjusting the composition of the molten ash.

Furthermore, in addition to the first or second means, a fourth means is provided with an ash discharge port of a molten ash cooling / recovery device for converting the molten ash into water slag and collecting the ash discharge port, in addition to the first or second means. It is equipped with a special discharge door.

In addition to the first or second means, the fifth means returns the recovered ash to the inside of the combustion furnace between the air preheater and the dust collector interposed in the exhaust gas passage of the combustion furnace and the combustion furnace. It has an ash recovery pipe.

Action According to the first means, the temperature of the molten coal ash discharged from the slag tap type combustion furnace is adjusted by the heating weir, and the coal ash is supplied as a raw material to the slag tap production apparatus to produce the slag tip, whereby the combustion is performed. The ash disposal cost can be reduced to zero, and the melting furnace required for the production of slag can be eliminated, which can greatly reduce the thermal energy. Also, since the additive supply nozzle is provided in the heating weir, it is possible to obtain a homogeneous mineral wool by adjusting the composition and melting point of the molten ash that fluctuates with changes in the composition of the fuel coal.

Further, according to the second means, the high temperature combustion gas of the combustion furnace is introduced into the cover body, and the molten ash can be kept warm in the heating weir and the sludge producing device, so that the thermal energy can be further reduced.

Furthermore, according to the third means, by adding an additive to the molten ash of the heating weir, the components and melting points of the molten ash that fluctuate with changes in the composition of the fuel coal are adjusted, and a homogeneous mineral wool is obtained. be able to.

Furthermore, according to the fourth means, the molten ash can be extracted from the heating weir and turned into slag when the operation of the boiler is stopped or a trouble occurs in the slag production apparatus, so that the boiler can be operated smoothly.

Further, according to the fifth means, the coal ash discharged from the exhaust gas passage along with the combustion gas from the combustion furnace is captured by the air preheater or the dust collector and melted back into the combustion furnace,
Most of the combustion ash can be used as a raw material for mineral wool, and it is extremely efficient.

Example An example of a coal-fired boiler facility according to the present invention will be described below with reference to the drawings.

In this boiler facility, an appropriate amount of lime is added to the combustion furnace 1 together with pulverized coal, the ash is melted and allowed to flow out of the hearth, and once stored in the heating weir 16, the temperature is controlled, and the molten ash B that has overflowed is slag. The basic structure is to drop the cotton wool D into the manufacturing apparatus 25 to manufacture it.

That is, in FIG. 1, 1 is a slag tap type (also referred to as wet bottom type) combustion furnace, in which a plurality of pulverized coal burners 2 are arranged facing the primary combustion chamber 1a, and a forced air from a pushing fan 3 is used. An air supply pipe 5 for supplying combustion air into the furnace via a heater 4 and a regenerative air preheater 8 is connected to the burner 2 and an air nozzle. Then, the extremely high temperature combustion gas A, which is burned while flowing downward from the burner 2, is turned upward in the hearth 1b, and the secondary combustion chamber
It is sent to 1c to heat the boiler water pipe group 6 and is discharged from the exhaust gas passage 7. In this exhaust gas passage 7, from the upstream side,
A regenerative air preheater 8, an electrostatic precipitator 9, and an induction fan 10 are interposed and connected to the chimney 11. Also, the air preheater 8
The coal ash (fly ash) captured by the electrostatic precipitator 9 is recovered in the combustion furnace 1 by the ash recovery air pipe 24.

The primary combustion chamber 1a is provided with a lime supply nozzle 12 that supplies lime necessary for desulfurization, and the lime of the lime supply hopper 13 is fed from the lime supply nozzle 12 into the primary combustion chamber 1a via the lime supply pipe 14A. By blowing in, the inside of the combustion furnace 1 is desulfurized, and the melting point of the coal ash contained in the fuel is lowered and melted, and this molten ash B is discharged from the slag outlet 15 formed in the hearth part 1b. are doing.

Reference numeral 16 is a heating weir provided on the outlet side of the slag outlet 15 of the hearth 1b, and a weir cover body 16b is provided above the weir body 16a to shut off the molten ash B in the weir body 16a from the outside air. The inlet 16c on one end side of the heating weir 16 is communicated with the slag outlet 15 through the molten ash introduction pipe 17, and the molten ash introduction pipe 17 is also used as a combustion gas introduction passage to remove the molten ash B from the furnace bottom 1b. Is introduced into the heating weir 16, and part of the high temperature combustion gas A in the combustion furnace 1 is introduced into the heating weir 16. Weir cover body 16b
Includes a gas cylinder to preheat the heating weir 16 at startup.
A gas burner 20 to which 18 fuel gases are supplied via a gas supply pipe 19 is arranged, and a temperature adjusting device 21 for adjusting the temperature of the molten ash B is provided. This temperature control device 21
The heating electrode 21a immersed in the molten ash B is
The applied current is controlled by the control device 22 on the basis of the detection signal of the infrared radiation thermometer 21b that detects the temperature of the molten ash B at the other end side outlet 16d of 6, and the molten ash B is controlled to a predetermined temperature. Further, the weir cover body 16b is provided with an additive supply nozzle 23 connected to the lime hopper 13 via a lime supply pipe 14B, and by adding lime to the molten ash B as necessary, The components can be adjusted and the melting point can be controlled.

Reference numeral 25 denotes a slag-cotton production apparatus, and a rotary disk 28 rotated at high speed by a disk drive motor 27 is disposed below the raw material dropping pipe 26 connected to the outlet 16d of the heating weir 16, and the rotary disk 28 An air jet nozzle 30 is provided which air-feeds the fibrous molten ash C generated by the rotating disk 28 near one side onto the forming conveyor 29 on the other side to form the slag D. And, these devices are shielded from the outside air by the forming part cover body 31, and the gas is connected to the lower part of the forming conveyor 29 of the forming part cover body 31 and the tip is connected to the exhaust gas passage 7 on the upstream side of the regenerative air preheater 8. The discharge pipe 32 is connected. The raw material dropping pipe 26 is also used as a gas introduction path, and the inside of the forming part cover body 31 is set to have a negative pressure larger than that inside the combustion furnace 1, so that the high temperature combustion gas A in the combustion furnace 1 is heated. The molten ash B is kept warm by being introduced into the weir 16 and the apparatus for producing cotton wool 25. Forming part cover body 31 of the slag manufacturing device 25
An unloading conveyor 33 to which the slag cotton D is transferred from the forming conveyor 29 is arranged outside.

Reference numeral 34 is a molten ash cooling and recovery device arranged at the lower part of one end side of the heating weir 16, and an ash discharge port 35 is formed on the one end side inclined wall of the weir main body 16a, and the inclined wall forming the weir main body 16a is an opening / closing cylinder. The device 36 constitutes a discharge door 37 capable of opening and closing the ash discharge port 35. And around the discharge door 37, the lower end is the cooling water tank.
Recovery part cover 39 for guiding molten ash B buried in cooling water 38
Combustion gas A which is attached and is discharged together with molten ash B
Leakage is prevented. A discharge conveyor 41 is provided outward from the bottom of the cooling water tank 38 to carry out a slag slag E of molten slag B in which molten ash B has been slagged by cooling water to a slag hopper 40. The molten ash cooling / recovery device 34 is used when the boiler is stopped or the slag production device 25 is stopped.

In the above structure, the ash content in the pulverized coal burned by the high-temperature combustion gas A in the combustion furnace 1 is melted by lime from the lime supply nozzle 12 to lower its melting point, and the molten ash B is converted into the hearth. It is introduced into the heating weir 16 from the slag outlet 15 of the portion 1b. At the heating weir 16, the molten ash B is cooled by the temperature adjusting device 21.
The temperature is adjusted by the
The lime is supplied to adjust the composition of the molten ash B and the melting point. Then, the same amount of overflow as the molten ash B dropped from the slag outlet 15 is supplied from the outlet 16d to the raw material dropping pipe 26 of the slag and cotton production device 25. A spinning method in which the molten ash is dropped onto a rotating disk 28 that rotates at a high speed and is made into wool is adopted, but a blowing method in which the molten ash is made into wool by high-pressure gas may be used depending on the purpose. The thus-produced mineral wool D is collected and carried out by the forming and carrying conveyors 29, 33, and processed into mats, boards, felts, etc. according to the purpose. In addition, when the boiler is stopped or any trouble occurs,
The discharge door 37 of the heating weir 16 is opened, and the molten ash B is dropped into a cooling water tank 38 provided below the ash discharge port 35 to turn into slag.

In order to prevent the temperature of the molten ash B from decreasing, the heating weir 16 and the slag production device 25 are shielded from the outside air by the weir cover body 16b and the forming section cover body 31, and the molten ash which also serves as a gas introduction path in the combustion furnace 1 is provided. By introducing a part of the high temperature combustion gas A in the combustion furnace 1 from the hearth 1b to the heating weir 16 and the slag production device 25, the structure is such that the introduction pipe 17 and the raw material dropping pipe 26 communicate with each other. The molten ash B can be effectively kept warm. The combustion gas A is returned from the gas exhaust pipe 32 to the exhaust gas passage 7 and is exhausted from the chimney 11 to the outside of the system.

Further, the coal ash (fly ash) which is entrained in the combustion gas A and discharged into the exhaust gas passage 7 and collected by the regenerative air preheater 8 and the electrostatic precipitator 9 is fed to the combustion furnace 1 by the ash recovery air pipe 24. It is sent to the inside and taken out as molten ash B from the hearth part 1b and used as a raw material for the slag D.

In order to clarify the possibility of wool formation by coal burning ash, we conducted a wool formation experiment using a raw material obtained by adding lime to coal ash (fly ash) discharged from an ordinary coal-fired boiler. Lime has a CaO content of 20, 30 and
It was added so as to be 40 wt%. Table 1 shows the chemical composition and melting point of the obtained molten ash B.

Melting is performed in a high frequency melting furnace, and the melting temperature is 50 from the melting point.
The molten ash was dropped on a steel rotating disk which was rotated at a high temperature of ~ 150 ° C and at a high speed of 5,000-20,000 rpm. Fig. 3 shows that the pouring temperature was 1450 for sample No. 2 (CaO content is 30 wt%).
An example of the relationship between the average fiber diameter and the particle content of the wool obtained at ˜1500 ° C. and the rotation speed of the disk is shown. Here, the fiber diameter and the particle content were measured according to the method of JIS A 9504. The average particle size tends to be smaller and the particle content tends to decrease as the rotation speed increases. When the disk rotation speed is 20,000 rpm, the average fiber diameter is about 3 μm and the particle content rate is about 3 wt%. ("Rockwool insulation material JI
SA 9504 "average fiber diameter: 7 μm or less, particle content: 4 wt% or less).

As described above, it is understood that the slag cotton can be produced from the coal ash as well as the blast furnace slag. It is expected that the composition of the coking coal will change in the actual machine operation, the melt flow point of the combustion ash will change, and therefore the conditions such as the appropriate pouring temperature and disk rotation speed for producing the slag cotton will easily change. Can be assumed. Therefore, in order to continuously produce mineral wool without changing the pouring temperature and disk rotation speed, the amount of lime added was changed according to the composition of the raw coal, and the temperature of the molten ash was measured using a radiation thermometer. It is necessary to control the pouring temperature by carrying out.

EFFECTS OF THE INVENTION As described above, according to the boiler equipment of the present invention, (1) since the slag extraction apparatus installed in the lower part of the combustion furnace is provided with the slag production apparatus through the heating weir, the coal-fired boiler The cost of disposing of combustion ash discharged from the plant will be almost zero. In order to supply lime from the lime supply nozzle to the combustion chamber, it is possible to desulfurize the inside of the combustion chamber, and to lower the melting point of ash, thereby receiving the molten ash discharged from the slag extraction port directly to the heating weir and reheating it, The large melting furnace required for the production of slag cotton is not required, and the thermal energy is significantly reduced compared to the conventional slag cotton manufacturing equipment produced by remelting blast furnace water slag slag. Be reduced. By the way, the heating temperature of the raw material is about
In contrast to 1500 ° C., in the present invention, the temperature is within about 100 ° C. Therefore, a simple calculation of the ratio between the present invention and the conventional required energy is about 1/15 or less. Less equipment and easy maintenance. Carbon dioxide emissions are reduced. When the composition of the fuel coal changes, by supplying lime from the additive supply nozzle to the heating weir, the composition and melting point of the molten ash can be adjusted, and a homogeneous mineral cotton can be obtained.

(2) Further, the heat energy can be further reduced by keeping the temperature of the molten ash by using the high temperature combustion gas of the combustion furnace.

(3) Furthermore, by adding an additive from the additive supply nozzle to the molten ash of the heating weir, the melting point and composition of the molten ash can be adjusted, and even if the composition of the fuel coal varies, it is uniform. You can get slag.

(4) Furthermore, by adding a molten ash cooling / recovery device to the heating weir, the molten ash can be reliably treated even if a trouble occurs in the slag production device.

(5) Further, by returning the coal ash (fly ash) captured in the exhaust gas passage to the inside of the furnace by the ash recovery pipe, these can be melted and used as a raw material for the mineral cotton, which also helps prevent air pollution.

[Brief description of drawings]

The drawings show an embodiment of the boiler equipment according to the present invention.
The figure is a schematic configuration diagram of a boiler facility, FIG. 2 is an enlarged configuration diagram of essential parts, and FIG. 3 is a graph showing the relationship between the fiber diameter and particle content of slag and the rotational speed of a rotating disk. 1 …… Slab tap type combustion furnace, 1b …… Heart floor, 2 …… Pulverized coal burner, 8 …… Air preheater, 9 …… Electrostatic precipitator, 12
...... Lime supply nozzle, 15 ...... Slag outlet, 16 …… Heating weir, 16a …… Weir body, 16b …… Weir cover body, 17 …… Melted ash introduction pipe, 21 …… Temperature control device, 21a …… Heating electrode, 21b
...... Infrared radiation thermometer, 22 ...... Control device, 23 …… Additive supply nozzle, 24 …… Ash recovery air pipe, 25 …… Mass cotton manufacturing device, 26 …… Raw material dropping pipe, 28 …… Rotating disk , 29 ... Forming conveyor, 30 ... Air injection nozzle, 31 ... Forming part cover body, 32 ... Gas discharge pipe, 34 ... Molten ash cooling and recovery device,
35 ... Ash discharge port, 36 ... Open / close cylinder device, 37 ... Discharge door, 38 ... Cooling water tank, A ... Combustion gas, B ... Molten ash,
C: Fibrous molten ash, D: Mineral wool, E: Water slag.

Front page continuation (72) Inventor Tadaomi Fujii, 5-3 28, Nishikujo, Konohana-ku, Osaka City, Osaka Prefecture Hitachi Shipbuilding Co., Ltd. (72) Seiichi Kotake, 5-28, Nishikujo, Konohana-ku, Osaka, Osaka No. Hitachi Shipbuilding Co., Ltd. (72) Inventor Shoichi Mohri 5-3 28 Nishikujo, Konohana-ku, Osaka City, Osaka Prefecture No. 28 Hitachi Shipbuilding Co., Ltd. (72) Masahiko Haitani, Nishikujo 5-chome, Konohana-ku, Osaka City, Osaka Prefecture 3-28 Hitachi Shipbuilding Co., Ltd. (72) Inventor Takashi Yudasaka 5-3-3 Nishikujo, Konohana-ku, Osaka City, Osaka Prefecture (28) Hitachi Shipbuilding Co., Ltd. (72) Inventor Michio Ishida Nishi, Konoka Ward, Osaka City, Osaka Prefecture 5-3 28 Kujo, Hitachi Shipbuilding Co., Ltd. (72) Masayuki Yasui Masako Yasui 3-53 28, Nishikujo 5-3-28, Nishikonohana-ku, Osaka City, Osaka Prefecture (56) Reference: JP-A-57-125777 ( JP, A)

Claims (4)

(57) [Claims] 1. A lime supply nozzle for supplying lime for desulfurization is provided in a combustion chamber of a slag tap type combustion furnace, and a heating weir having a temperature adjusting device for molten ash is provided at a slag outlet formed in a hearth. The coal burning is characterized in that the outlet of the heating weir is provided with a slag production device to which a raw material inlet is connected, and the heating weir is provided with an additive supply nozzle for supplying lime for component adjustment and melting point adjustment. Boiler equipment. 2. A heating weir and a slag production apparatus are provided with a cover body for shielding from the outside air, and a gas introduction path for introducing combustion gas in the combustion furnace into the cover body is provided between the combustion furnace and the cover body. The coal-fired boiler equipment according to claim 1, which is provided. 3. A heating weir is provided with an ash discharge port of a molten ash cooling / recovery device for granulating and recovering molten ash, and an ash discharge port is provided at this ash discharge port. The coal-fired boiler facility according to 1 or 2. 4. An ash recovery pipe for returning the recovered ash to the inside of the combustion furnace is provided between the combustion furnace and the air preheater and dust collector interposed in the exhaust gas passage of the combustion furnace. Item 1. A coal-fired boiler facility according to Item 1 or 2.