JPH0424410A - Coal firing boiler - Google Patents

Abstract

PURPOSE:To obviate the expense of combustion ash disposal and the provision of an ash melting furnace and remarkably save heat energy by a method wherein coal ash discharged from a slag tap firing type incinerator is controlled for temperature in a heating weir and supplied to a slag wool manufacturing apparatus as raw material to produce slag wool. CONSTITUTION:The melting point of ash component, which is produced when pulverized coal is burned by high temperature combustion gas in an incinerator 1, is lowered by adding lime fed from a lime feed nozzle, and the molten ash B is led from a slag blow-down port 15 of a hearth 1b to a heating weir 16. In the heating weir 16, the temperature of the molten ash is controlled and lime is fed into the ash from an additive feed nozzle 23 so that the components and the melting point of the molten ash B are adjusted. The prepared molten ash B overflows from an outlet 16d and is supplied into a raw material feed pipe 26 of a slag wool manufacturing apparatus 25 at a feed rate equivalent to the flow rate of the molten ash B falling down from the slag blow-down port 15. Slag wool D produced is gathered and carried by molding and transfer conveyers 29 and 33 and processed to mats, boards, felt and others corresponding to purpose.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is a slag tap type (wet bottom type) that discharges the ash in the fuel as ash as the combustion temperature is extremely high.
The present invention relates to coal-fired boiler equipment in which a combustion furnace is added with a slag cotton production device for producing slag cotton using the molten ash as a raw material.

How to dispose of ash emitted from conventional coal-fired boilers is a serious issue, and there is a great social need for its effective use. Most of the coal ash discharged from conventional boilers is so-called fly ash.The unprocessed material is used for landfill and soil improvement, and the semi-processed material is used as cement raw material, ready-mixed concrete additive, roadbed material, and artificial material. It is used as a lightweight aggregate, and is being considered as a highly processed material such as sound absorbing materials and various building materials.

On the other hand, the raw materials for slag cotton currently manufactured are mainly blast furnace slag, silica stone, basalt, andesite, etc., and are remelted in melting furnaces such as electric furnaces and cupolas with the addition of composition regulators as necessary. A method is used in which the molten material is supplied to a cotton machine and made into fibers by centrifugal force or fluid pressure such as compressed air or steam.

Problems to be Solved by the Invention Coal-fired boilers have a problem with coal ash disposal compared to heavy oil-fired boilers, and in order to use the discharged ash as a highly processed material, the manufacturing cost required for the combustion process etc. is high. There is a point in saying that it is expensive.

On the other hand, there are problems with the production of slag, such as the high energy cost for melting raw materials and the large amount of carbon dioxide gas emitted during production.

The present invention raises the combustion temperature and lowers the melting point of ash by adding lime necessary for in-furnace desulfurization, and the ash is discharged from a slag tap type combustion furnace in which the ash is discharged in a molten state from an extraction hole in the hearth. The object of the present invention is to provide coal-fired boiler equipment that can solve the above problems 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 to install a temperature adjustment device for molten ash at the outlet of the slag extraction port formed in the hearth of the slag tap type combustion furnace. A slag manufacturing apparatus is provided in which a heating weir is provided, and a raw material input port is connected to an outlet of the heating weir.

In addition to the first means, the second means includes providing a cover body for shielding the heating weir and the slag manufacturing equipment from the outside air, and disposing a cover body between the combustion furnace and the cover body so that the combustion gas in the combustion furnace A gas introduction path is provided to introduce gas into the cover body.

Furthermore, a third means is one in which, in addition to the first or second means, a heating weir is provided with an additive supply nozzle for adjusting the components of the 78 melted ash.

Furthermore, in addition to the first or second means, the fourth means is to provide the heating weir with an ash discharge port of a molten ash cooling and recovery device that collects the molten ash by turning it into slag, and the ash discharge port can be opened and closed freely. What if we installed a discharge door?

Further, in addition to the first or second means, a fifth means includes returning the collected ash to the combustion furnace between an air preheater and a dust collector interposed in the exhaust gas passage of the combustion furnace and the combustion furnace. It is equipped with a concave ash collection pipe.

According to the first means, the temperature of the molten coal ash discharged from the slag tap combustion furnace is adjusted by the heating weir, and #,
By supplying the slag as a raw material to the slag production equipment and manufacturing the slag, the cost of disposing of combustion ash can be reduced to 1':J, and the melting furnace required to produce the slag is not required, resulting in significant savings in thermal energy. can.

Further, according to the second means, the high temperature combustion gas from the combustion furnace can be introduced into the cover body to keep the molten ash warm in the heating weir and the slag manufacturing apparatus, so that thermal energy can be further saved.

Furthermore, according to the third means, by adding additives to the molten ash in the heating weir, the components and melting point of the molten ash, which fluctuate with changes in the composition of the fuel coal, are adjusted, thereby obtaining homogeneous mineral slag. be able to.

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

According to the fifth means, coal ash discharged from the exhaust gas passage along with the combustion gas from the combustion furnace is captured by an air preheater or a dust collector, and returned to the combustion furnace and melted. Most of this can be used as raw material for slag cotton, which is extremely efficient.

EXAMPLE Hereinafter, an example of the coal-fired boiler equipment according to the present invention will be described based on the drawings.

This boiler equipment adds an appropriate amount of lime together with pulverized coal to a combustion furnace 1, melts the ash, flows it out from the hearth, and then stores it in a heating weir 16 to control the temperature. The basic structure is to produce cotton slag by dropping it into the cotton production device 25.

That is, in FIG. 1, 1 is a slag tap type (also called wet bottom type) combustion furnace, in which a plurality of pulverized coal burners 2 are arranged facing a primary combustion chamber 1a, and steam air is supplied from a forced fan 3. An air supply pipe 5 that supplies combustion air into the furnace via the heater 4 and the regenerative air preheater 8 is connected to the burner 2 and the air nozzle. The extremely high-temperature combustion gas A, which is combusted while flowing downward from the burner 2, is diverted upward at the hearth part 1b, sent to the secondary combustion chamber IC, and heats the boiler water tube group 6, and the exhaust gas It is discharged from passage 7. This exhaust gas passage 7 includes, in order from the upstream side, a regenerative air preheater 8, an electric precipitator 9, and an induction fan 1.
0 is interposed and connected to the chimney 11. In addition, coal ash (
fly ash) is collected into the combustion furnace 1 through the ash collection air pipe 24.

The primary combustion chamber 1a is provided with a lime supply nozzle 12 that supplies lime necessary for desulfurization, and a lime supply hopper 13.
The lime is supplied to the lime supply nozzle 12 through the lime supply pipe 14A.
By blowing into the primary combustion chamber 1a from
It desulfurizes the inside of the fuel, lowers the melting point of the coal ash contained in the fuel, melts it, and discharges this molten ash B from a slag extraction port 15 formed in the hearth portion 1b.

Reference numeral 16 denotes a heating layer provided on the outlet side of the slag extraction port 15 of the hearth portion 1b, and a weir cover body 16b is provided on the upper part of the weir body 16a to block the molten ash B in the weir body 16a from the outside air. One end side opening 16c of the heating layer 16 is communicated with the slag extraction port 15 via a molten ash introduction pipe 17, and this molten ash introduction pipe 17 is also used as a combustion gas introduction path, so that the molten ash flows from the furnace bottom 1b. B is introduced into the heating weir 16, and at the same time, a part of the high temperature combustion gas A in the combustion furnace I is introduced into the heating weir 16. The weir cover body 16b has a heating layer 1 at the time of startup.
A gas burner 20 to which fuel gas from a gas cylinder 18 is supplied via a gas supply pipe 19 is provided to preheat the molten ash B, and a temperature adjustment device 2 for adjusting the temperature of the molten ash B.
1 is provided. This temperature adjustment device 21 has a heating electrode 21a immersed in molten ash B based on a detection signal from an infrared radiation thermometer 21b that detects the temperature of molten ash B at the other end side outlet 16d of the heating layer 16. The applied current is controlled by the control device 22 to control the molten ash B to a predetermined temperature. In addition, the weir cover body 16b includes a lime hopper 1.
3 is provided with an additive supply nozzle 23 connected to the lime supply pipe 14E3, and by adding lime to the molten ash B as necessary, component adjustment and melting point control can be performed.

Reference numeral 25 denotes a slag manufacturing device, in which a rotating disk 28 rotated at high speed by a disk drive motor 27 is disposed below a raw material dropping pipe 26 connected to an outlet 16d of the heating layer 16, and one side of the rotating disk 28 is provided. The fibrous molten ash C generated by the rotating disk 28 near the side is transferred to the forming conveyor 2 on the other side.
an air injection nozzle 30 that blows air onto the slag 9 to form a slag floc;
is provided. These devices are isolated from the outside air by the forming section cover body 31, and a gas gas whose tip is connected to the exhaust gas passage 7 upstream of the regenerative air preheater 8 is provided at the bottom of the forming conveyor 29 of the forming section cover body 31. A discharge pipe 32 is connected. The raw material drop pipe 26 is also used as a gas introduction path, and the negative pressure inside the forming part cover body 31 is set to be larger than that inside the combustion furnace 1.
High-temperature combustion gas A in the combustion furnace 1 is introduced into the heating layer 16 and the slag production device 25 to keep the molten ash B warm. A conveyor 3 for carrying out the slag from the forming conveyor 29 to the outside of the forming part cover body 31 of the slag manufacturing device 25.
3 is arranged.

Reference numeral 34 denotes a molten ash cooling and recovery device disposed at the lower part of one end of the heating layer 16, and an ash discharge port 3 is provided on the inclined wall of one end of the weir body 16a.
5 is formed, and the inclined wall forming the weir body 16a is configured as a discharge door 37 which can open and close the ash discharge port 35 by an opening/closing cylinder device 36. A recovery section cover 39 for guiding molten ash B, whose lower end is submerged in the cooling water of the cooling water tank 38, is attached around the discharge door 37 to prevent leakage of the combustion gas A discharged together with the molten ash B. ing. A discharge conveyor 41 is disposed outward from the bottom of the cooling water tank 38 to carry out a slag slag E in which molten ash B has been turned into slag by cooling water to a slag hopper 40 . The molten ash cooling and recovery device 34 is used when the boiler is stopped or the slag manufacturing device 25 is stopped.

In the above configuration, the ash in the pulverized coal burned by the high-temperature combustion gas A in the combustion furnace 1 is lowered in melting point by the lime from the lime supply nozzle 12 and becomes molten, and this molten ash B is The slag is introduced into the heating 016 from the slag outlet 15 in the floor 1b. In the heating layer 16, the temperature of the molten ash B is adjusted by a temperature adjustment device 21, and lime is supplied from an additive supply nozzle 23 to adjust the composition and melting point of the molten ash B. And slag extraction port 15
An overflow amount equivalent to the molten ash B falling from the slag is supplied from the outlet 16d to the raw material drop pipe 26 of the slag manufacturing apparatus 25. This molten ash is collected by a rotating disk 28 that rotates at high speed.
A spinning method is used in which the material is dropped onto the surface to form wool, but depending on the purpose, a blowing method in which the material is made into wool using high-pressure gas may also be used. The slag produced in this way is collected and carried out by forming and carrying out conveyors 29, 33, and processed into mats, boards, felt, etc. according to the purpose.

Note that when the boiler is stopped or some trouble occurs, the discharge door 37 of the heating layer 16 is opened and the molten ash B is dropped into a cooling water tank 38 provided below the ash discharge port 35 and turned into slag.

In order to prevent the temperature of the molten ash B from decreasing, the heating unit 116 and the slag manufacturing device 25 are shielded from the outside air by the weir cover body 16b and the forming part cover body 31, and the molten ash introduction is carried out in the combustion furnace 1 and also as a gas introduction path. Pipe 17 and raw material drop pipe 26
By introducing a part of the high-temperature combustion gas A in the combustion furnace 1 from the hearth part 1b to the heating layer 16 and the slag manufacturing device 25, the molten ash B can be extremely effectively communicated through the
can be kept warm. This combustion gas A is returned to the exhaust gas passage 7 from the gas exhaust pipe 32 and is discharged from the chimney 11 to the outside of the system.

In addition, coal ash (fly ash) which is discharged into the exhaust gas passage B7 along with the combustion gas A and is collected by the regenerative air preheater 8 and the electric precipitator 9 is transferred to the combustion furnace 1 through the ash recovery air pipe 24. The molten ash B is taken out from the hearth part 1b and used as a raw material for slag milling.

In order to clarify the possibility of wool formation using coal combustion ash, we conducted a wool formation experiment using a raw material obtained by adding lime to coal ash (fly ash) discharged from a normal coal-fired boiler. CaO content in molten ash of lime is 20.30
and 40wt%. Table 1 shows the chemical composition and melting point of the obtained Fi ash B.

(Left below) Melting is done in a high-frequency melting furnace, and the melting temperature is 50° below the melting point.
~150℃ higher temperature, 5,000~20,000r
The molten ash was dropped onto a steel rotating disk that was rotating at high speed. Figure 3 shows sample Nci2 (CaO content is 30wt).
%), the pouring temperature was set at 1450 to 1500°C, and an example of the relationship between the average m-fiber diameter and particle content of the wool obtained and the rotation speed of the disk is shown. Here, the fiber diameter and particle content were measured according to the method of JIS^9504.
As the rotational speed increases, the average particle diameter tends to become smaller and the particle content decreases, and when the disk rotational speed is 20,000
At 0 rpm, the average fiber diameter is approximately 3 μm and the particle content is approximately 3 wt%, satisfying the JIS value ([Rock wool insulation material JIS^9504 J average fiber diameter = 7 μm or less, particle content: 4 wt% or less] The value is

Thus, it can be seen that slag cotton can be produced from coal ash as well as from blast furnace slag. During actual twisting operation, it is expected that the composition of the coking coal will change and the melting point of the combustion ash will change, which will change the conditions such as the appropriate pouring temperature and disk rotation speed for producing slag cotton. It can be easily assumed. Therefore, in order to continuously produce slag without changing the pouring temperature and disk rotation speed, we changed the amount of lime added depending on the composition of the coking coal and measured the temperature of the molten ash using a radiation thermometer. It is necessary to control the pouring temperature by doing this.

Effects of the Invention As described above, according to the boiler equipment of the present invention, (1) Since the slag production device is installed at the slag extraction port installed at the bottom of the combustion furnace via a heating layer, The cost of disposing of combustion ash discharged from the boiler becomes almost zero. ■Since molten ash discharged from coal-fired boilers is used, there is no need for a large melting furnace required for the production of slag cotton, compared to conventional slag cotton manufacturing equipment that is manufactured by remelting blast furnace slag slag. As a result, thermal energy is significantly saved and running costs are therefore significantly reduced. Incidentally, the heating temperature of the raw materials is approximately 1500°C in the conventional method, whereas
In the present invention, the temperature is within about 100° C., so if the ratio of the required energy of the present invention and the conventional method is simply calculated, it will be about 1715 or less. ■There are few facilities and maintenance is easy. ■Reduced carbon dioxide emissions.

(2) Furthermore, thermal energy can be further saved by keeping the molten ash warm using the high-temperature combustion gas of the combustion furnace.

(3) Furthermore, by adding additives to the molten ash in the heating layer from the additive supply nozzle, the melting point and components of the molten ash can be adjusted, and even if the composition of the fuel coal changes, it will remain homogeneous. You can get slag cotton.

(4) Furthermore, by adding a 7B molten ash cooling and recovery device to the heating layer, even if trouble occurs in the slag manufacturing device, the molten ash can be reliably processed.

(5) In addition, by returning the coal ash (fly ash) captured in the exhaust gas passage into the furnace through the ash recovery pipe, it can be used as a raw material for slag, which also helps prevent air pollution. .

[Brief explanation of the drawing]

The drawing shows an example of actual repair of the boiler equipment according to the present invention, and the first
Figure 2 is a schematic diagram of the boiler equipment, Figure 2 is an enlarged diagram of the main parts, and Figure 3 is a graph showing the relationship between the fiber diameter and particle content of slag and the rotational speed of the rotating disk. 1... Slab tap type combustion furnace, 1b... Hearth part, 2
...Pulverized coal burner, 8...Air preheater, 9...Electrostatic precipitator, 12...Lime supply nozzle, 15...Slag extraction port, 16...Heating layer, 16a...・Weir body, 1
6b... Forward cover body, 17... Molten ash introduction pipe, 21
...Temperature adjustment device, 21a...Heating electrode, 21b
... infrared radiation thermometer, 22 ... control device, 23.
... Additive supply nozzle, 24 ... Air pipe for ash recovery, 2
5... Slags manufacturing equipment, 26... Raw material drop pipe, 28
...Rotating disk, 29... Forming conveyor, 30...
・Air injection nozzle, 31...formation part cover body, 32・
... Gas discharge pipe, 34 ... Molten ash cooling recovery device, 35
...Ash discharge port, 36...Opening/closing cylinder device, 37.
...Discharge door, 38...Cooling water tank, A...Combustion gas,
B... Molten ash, C... Fibrous molten ash, D... Slag cotton, E... Water slag slag.

Claims (1)

[Scope of Claims] 1. A heating weir having a molten ash temperature regulating device is provided at the outlet of the slag extraction port formed in the hearth of the slag tap type combustion furnace, and a raw material input port is connected to the outlet of the heating weir. Coal-fired boiler equipment characterized by being equipped with a slag manufacturing equipment. 2. A cover body is provided on the heating weir and the slag manufacturing equipment to shield it from the outside air, and a gas introduction path is provided between the combustion furnace and the cover body to introduce the combustion gas in the combustion furnace into the cover body. The coal-fired boiler equipment according to claim 1, characterized in that: 3. The coal-fired boiler equipment according to claim 1 or 2, wherein the heating weir is provided with a nozzle for supplying an additive for adjusting the components of the molten ash. 4. Claim 1 or 2, characterized in that the heating weir is provided with an ash discharge port of a molten ash cooling and recovery device for recovering molten ash by converting it into water slag, and this ash discharge port is provided with a discharge door that can be opened and closed freely. Coal-fired boiler equipment described. 5. Claim 1 or 5, characterized in that an ash recovery pipe is provided between the combustion furnace and the air preheater and dust collector interposed in the exhaust gas passage of the combustion furnace to return the collected ash into the combustion furnace. Coal-fired boiler equipment according to 2.