JPH06137535A - Burner for boiler - Google Patents

Abstract

PURPOSE:To completely burn slag to ash by providing a main combustion grating and an auxiliary combustion fire grate. CONSTITUTION:Biological fuel F such as bagasse, wood chips, etc., scattered in a combustion chamber 2 by a fuel spreader 4 is partly burned in space, and the residue is mainly burned on a main burning fire grate 5. When the burned slag E is deposited on the fire grate 5, steam S is injected from a steam injection hole 11, and hence the slag E is urged forward. The urged slag E is stored on an auxiliary burning grating 13 for a predetermined time, burning auxiliary air 15 is supplied from below during the period, and hence unburned matter is automatically burned. Thus, the slag E on the grating 13 can be burned to ash containing no unburned matter at all.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a boiler of the type that spreads and burns biofuels such as sugar cane residue, corn stalks (hereinafter referred to as bagasse), and wood chips, so-called inclined steam. The present invention relates to improvement of a combustion device of a boiler using an injection type grate.

[0002]

2. Description of the Related Art In a boiler that uses bagasse, wood chips, etc. as a fuel, a method of spraying fuel onto a grate by a mechanical sprayer or an air sprayer and then spraying and burning these fuels is often adopted. FIG. 3 shows an example of a conventional combustion apparatus of this type of boiler. In the figure, 1 is a boiler, 1a is a water cooling wall, 1b is a combustion air supply hopper, 2 is a combustion chamber, and 3 is a combustion chamber.
Is a fuel supply hopper, 4 is a fuel spreader, 5 is a main combustion grate, 6 is an ashes chute, 7 is a water tank, 8 is an air supply pipe, 9 is a steam supply pipe, 10 is a water cooling pipe, 11 is a steam injection hole, Reference numeral 12 is combustion air.

The main combustion grate 5 which constitutes the combustion device of the boiler is arranged in an inclined shape in the vicinity of the bottom surface of the combustion chamber 2, and the steam S supplied from the steam supply pipe 9 is provided on the upper surface thereof.
Is provided with a large number of vapor injection holes 11 for ejecting the water toward the front. Further, the main combustion grate 5 is a cooling pipe 1.
0, and the water W is indirectly cooled by the water W flowing through the water cooling pipe 10.

The fuel F such as bagasse and wood chips is dispersed into the combustion chamber 2 by the pneumatic fuel spreader 4, and the small and lightweight fuel F carries out so-called floating combustion in the combustion chamber 2. Also,
The large and heavy fuel F drops onto the main combustion grate 5 and is burned on its upper surface. Further, when the combustion residue E on the upper surface of the main combustion grate 5 becomes thick due to the combustion of the fuel F for a certain time, the steam S is ejected from the steam injection holes 11. As a result, the combustion residue E accumulated on the main combustion grate 5 is pushed out toward the ash extraction chute 6 side, and the upper surface of the main combustion grate 5 is cleaned.

By the way, when the fuel F such as bagasse or wood chips is crushed to a relatively uniform size, even if the combustion apparatus of the boiler including the main combustion grate 5 as shown in FIG. F can be efficiently and completely burned. However, if the size and weight of the fuel F are not uniform,
The large and heavy fuel F is concentratedly dropped above the front end portion 5a of the main combustion grate 5, and as a result, the large fuel F is directly dropped into the ashing chute 6 without being burned. In addition, even in the fuel F dispersed on the main combustion grate 5, when a large one ejects the steam S to clean the upper surface of the main combustion grate 5, the combustion is completed by the ejected steam S. It will be extinguished before, and will be discharged to the ash extraction chute 6 side in an unburned state. Furthermore, the combustion chamber 2
Even in the case of the fuel F that is floatingly combusted inside, since the inside of the combustion chamber 2 is vigorously stirred by the air and the combustion gas from the spreader 4, it may fall into the ashing chute 6 without being burned. is there.

It is possible to prevent the unburned fuel F from directly falling into the ashing chute 6 by increasing the length of the main combustion grate 5. However, when the combustion residue E is pushed forward by the jet of the steam S,
The fuel extinguished by the jetted steam becomes an unburned substance and is pushed out downward. Moreover, since this unburned substance does not have an ignition source, it does not self-combust, and remains in the ashing chute 6 as it is. Fall down. Therefore, simply increasing the length of the main combustion grate 5 cannot achieve the reduction of unburned substances.

According to the results of the investigation, 6 to 7% of the fuel F sprayed from the fuel spreader 4 into the combustion chamber 2 is discharged to the ashing chute 6 side in a so-called unburned state. This type of combustion device (for example, traveling type grate and damping type grate has an emission rate of 2 to 3 of unburned fuel).
%), A large amount of unburned fuel is ashed chute 6
It has been discharged inside. Therefore, in the combustion apparatus using the main combustion grate 5 of this kind, there is a problem that not only the loss of fuel energy is increased, but also when the combustion residue E is discarded, environmental pollution occurs.

[0008]

DISCLOSURE OF THE INVENTION The present invention has the above-mentioned problems in a boiler using a conventional bagasse, wood chips, etc. as a fuel and a tilted / steam injection type grate as a combustion device. In order to solve the problems such as the amount of fuel discharged to the ashing chute side in the combustion state increases the energy loss, and the environmental pollution occurs due to the dumping of the combustion residue E with many unburned substances. The present invention provides a combustion apparatus for a boiler, which is capable of almost completely combusting the entire amount of the fuel dispersed in the boiler main body even when the sizes of the fuel are uneven.

[0009]

As shown in FIG. 1, the present invention includes a main combustion grate 5 for burning a fuel F such as bagasse or wood chips scattered into a combustion chamber 2 by a fuel spreader 4; The auxiliary combustion grate 13 which is arranged below the front end of the grate 5 and which stores the combustion residue E and the like discharged from the main combustion grate 5 for a certain period of time and then discharges this to the outside is the basic configuration of the invention. The present invention is characterized in that the unburned matter contained therein is completely self-combusted while the combustion residue E is stored on the auxiliary combustion grate 13.

[0010]

The fuel F such as bagasse scattered by the fuel spreader 4 into the combustion chamber 2 partially burns in space, and the rest burns mainly on the main combustion grate 5. When the combustion residue E on the main combustion grate 5 is piled up, the steam S is ejected from the steam ejection hole 11, and the combustion residue E is pushed forward. The extruded combustion residue E is stored on the auxiliary combustion grate 13 for a certain period of time, and the auxiliary combustion air 15 is supplied from the lower part during that time, so that the unburned substances inside are self-combusted. As a result, the combustion residue E on the auxiliary combustion grate 13 becomes complete ash without any unburned substances. After a certain period of time, the auxiliary combustion grate 13 is activated, and the combustion residue E stored above is dropped into the water tank 7 below,
The fire is extinguished here.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a main part of a boiler provided with a combustion device according to a first embodiment of the present invention. In FIGS. 1 and 2, the names and reference signs E, F, and
The names of the substances indicated by S and W are the same as those in FIG. 3, respectively. In the present invention, the ash is located below the front end 5a of the main combustion grate 5 and above the ashing chute 6. It is characterized in that a small dipping type auxiliary combustion grate 13 which also serves as a reservoir is provided.

The main combustion grate 5 is arranged in an inclined shape, and a plurality of steam injection holes 11 for ejecting the steam S toward the front are formed on the upper surface of the grate.
In the present specification, the main combustion grate 5 will be referred to as a tilted / steam injection type grate in the following description. On the other hand, the small-sized damping-type auxiliary combustion grate 13 is disposed substantially horizontally in the ash extraction chute 6, and one end thereof is rotatably supported by a support shaft 13a. Further, the auxiliary combustion grate 13 is large and heavy in the fuel F supplied into the combustion chamber 2 by the fuel spreader 4, and the steam S.
The combustion debris E and the like extruded forward by the jet of air are temporarily stored on the upper surface side thereof, and during that time, the amount of heat of the combustion debris E and unburned matter is utilized to push the blower 14 from below.
By supplying the combustion auxiliary air 15 by means of this, the unburned substances contained therein are gradually burned to complete ash. The auxiliary combustion grate 13 itself is formed in a structure having air permeability. Furthermore, the auxiliary combustion grate 13 is manually or automatically operated in the direction of the arrow, whereby the unburned material is completely combusted during storage and the combustion residue E, which is only ash, falls into the water tank 7. . The auxiliary combustion grate 13 is used for 1 hour to 8 hours by using a timer or the like.
It may be operated at a rate of once per hour, or starting from the injection of the steam S from the steam injection holes 11 of the main combustion grate 5 and 3 to 5 hours after this, the auxiliary combustion grate 13
May be automatically activated.

In this embodiment, a so-called flat plate type damping grate is used as the auxiliary combustion grate 13 and one side of the damping grate is rotatably supported, but as shown in FIG. You may make it support two grate with both sides open.

Next, the operation of the boiler combustion apparatus according to the present invention will be described. Fuel F such as bagasse is sprayed from the air spray type fuel spreader 4 into the combustion chamber 2. About 50 to 75% of the sprayed fuel F is suspended in the combustion chamber 2, and the remaining 50 to 25% falls on the main combustion grate 5 and the auxiliary combustion grate 13 where they are sequentially burned. . When the combustion is performed for a certain period of time, the steam S is ejected from the steam injection hole 11, whereby the ash, unburned matter, raw bagasse, etc. accumulated on the main combustion grate 5 are pushed forward, About 90% falls onto the auxiliary combustion grate 13 and is stored there.

The ash, unburned materials and the like stored on the auxiliary combustion grate 13 maintain a temperature exceeding about 250 ° C.,
By sending a small amount of auxiliary air 15 for combustion from below the grate 13, the unburned materials and the like inside are burned to form complete ash. After the pre-determined storage time has elapsed, the auxiliary combustion grate 13 is actuated, and the storage material that has been completely ashed by self-combustion during storage is dropped into the water tank 7 and extinguished. (Not shown) and the like is discharged to the outside.

[0016]

According to the present invention, the combustion apparatus of the boiler is formed by the inclined / steam injection type main combustion grate 5 and the auxiliary combustion grate 13 arranged below the tip of the main combustion grate 5. The combustion residue E or the like extruded from the combustion grate 5 is stored on the auxiliary combustion grate 13 for a certain period of time and then discharged below the ash discharge chute 6. As a result, the unburned fuel F that has been sprayed to the front end portion of the main combustion grate 5 due to its heavy weight and the uncombusted fuel F that has been extinguished by the injected steam and has been extruded from the main combustion grate 5 in an unburned state. The substances and the like are completely burned on the auxiliary grate 13 during storage, and the unburned substances in the combustion residue E discharged downward from the ashing chute 6 are extremely small. According to the results of the actual machine test, the content of unburned substances in the combustion residue E discharged to the outside is 1% or less, and it is possible to obtain the excellent combustion efficiency over that of the traveling type grate and the damping type grate. . As described above, the present invention has high practical utility in terms of effective use of fuel energy and prevention of pollution at the dumping place of combustion residues, despite the simple configuration.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a main part of a boiler equipped with a combustion device according to the present invention.

FIG. 2 shows a part of the cross section of the main combustion grate.

FIG. 3 is a vertical cross-sectional view showing a main part of a boiler provided with a combustion device including a conventional inclined / steam injection type main combustion grate.

[Explanation of symbols]

F is fuel, E is combustion residue, S is steam, W is water, 1 is a boiler, 1a is a water cooling wall, 1b is a combustion air supply hopper, 2 is a combustion chamber, 3 is a fuel supply hopper, 4 is a fuel spreader, 5
Is a main combustion grate, 5a is a front end of the grate, 6 is an ashing chute, 7 is a water tank, 8 is an air supply pipe, 9 is a steam supply pipe,
10 is a water cooling pipe, 11 is a steam injection hole, 12 is combustion air,
13 is an auxiliary combustion grate, 13a is a support shaft, 14 is a forced draft fan, and 15 is combustion auxiliary air.

Claims (4)

[Claims] 1. A main combustion grate (5) for burning a fuel (F) such as bagasse and wood chips scattered in a combustion chamber (2) by a fuel spreader (4); and the main combustion grate (5).
Of the auxiliary combustion grate (13), which is arranged below the front end of the fuel cell and stores the combustion residues (E) discharged from the main combustion grate (5) for a certain period of time and then discharges this to the outside. A boiler combustion device characterized by the above. 2. A grate (5) of the type in which a main combustion grate (5) is mounted on a water cooling pipe (10) and arranged in an inclined manner, and further has a plurality of steam injection holes (11). The boiler combustion apparatus according to claim 1, wherein the auxiliary combustion grate (13) is a flat plate-shaped or semi-circular grate in which the auxiliary combustion grate (13) is rotatably supported in the ashing chute (6). 3. A configuration in which the auxiliary combustion grate (5) is a flat plate-shaped or semi-circular grate to which the combustion auxiliary air (15) is supplied from below, and self-burns the unburned materials temporarily stored. The boiler combustion apparatus according to claim 1 or 2. 4. The combustion residue (E) is automatically discharged downward after a lapse of a fixed time after receiving the combustion residue (E) from the main combustion grate (5) in the auxiliary combustion grate (5). The combustion apparatus for a boiler according to claim 1, 2 or 3, which is configured.