JPH0285602A - U-shaped burning furnace - Google Patents

Abstract

PURPOSE:To reduce an unburnt discharge by keeping a favorable combustion state by eliminating a drift or short pass in a furnace, by providing a partition wall partitioning a hopper shape on the bottom part of the furnace into a front and rear wall sides. CONSTITUTION:A flat-platelike solid wall 22 is mounted on the bottom part, that is, a hopper part (a) of a space 1 of a furnace and the hopper part (a) is divided into a front and rear part furnace bottom spaces 23a, 23b. Since it becomes that stream of a front and rear wall burners 13a, 13b injected toward a hopper space of the bottom part of the furnace do not interfere with each other by being prevented by the wall 22 and, moreover, raised by inverting swiftly along the wall, a phenomenon exerting a bad influence on combustion such as a drift or short pass in the furnace is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a U-shaped combustion furnace, and in particular to a U-shaped combustion furnace suitable for extending the residence time of flame-retardant fuel in the furnace and combusting the fuel.
Concerning a letter-shaped combustion furnace.

[Conventional technology]

Conventionally, gas, oil, coal, etc. have been used as fuel for boilers and the like, but after the oil shock, various fuels are being used from a cost standpoint. Among these fuels, gas,
Oil etc. have relatively good combustibility, but coal, especially semi-anthracite,
Coal or petroleum coke, etc., which has a fuel ratio (solid carbon content/volatile content ratio in coal) of 6 or more called anthracite,
It takes a lot of effort to burn it. As a furnace for burning these flame-retardant fuels, there is a U-shaped combustion furnace (also called a wing furnace) in which the flow of flame or combustion gas in the furnace space is U-shaped.

Fig. 16 is a sectional view of a conventional U-shaped combustion furnace;
The figure is a sectional view taken along the line CC in FIG. 16, and FIG. 18 is a flowchart of the jet flow in FIG. 16. In the figure, the furnace 1 has four front walls 2, a rear wall 3, a left side wall 4, and a right side wall 5.
It consists of upper and lower ceiling walls 6 and bottom walls 7a and 7b. The furnace bottom walls 7a and 7b are tilted and installed to discharge slag, ash, etc., and form a hopper part (a). The front wall 2 and the rear wall 3 consist of an abdomen (B), a shoulder (C), and a neck (D).
C) is horizontal or somewhat inclined.

The burner 13 is attached to the shoulders (c) of the front wall 2 and the rear wall 3. Wind boxes 12 are arranged on the front wall 2 and the rear wall 3, and supply air to the burner 13 and the air ports 14 provided on the front and rear walls 2.3. A fuel 17 such as anthracite powder is mixed with air as a fuel-air mixture 19,
) Almost downward from the march 13, that is, the furnace bottom walls 7a, 7
It is injected in the direction b. The flame or combustion gas 20 reversely rises near the furnace bottom space 48 and is discharged from the furnace outlet 21 through the neck (d). As mentioned above, the hopper part (a)
A discharge port 15 for discharging slag, ash, etc. is arranged at the bottom of the tank.

In such a furnace, the residence time of the fuel can be extended, so combustion efficiency is increased even when using flame-retardant fuel.
It is possible to reduce the amount of unburned fuel that is discharged.

However, the jet flow injected from the burner 13 may not follow a U-shaped trajectory, and either the jet flow from the burner 13 on the front wall 2 or the rear wall 3 may become a short-path flow 50. In FIG. 18, the flow on the side of the rear wall 3 becomes a vortex 49 and sinks to the bottom space 48 of the hopper part, and the flow on the side of the front wall 2 is a short path that reverses and rises immediately after being injected from the burner 13. The current is 50. When a drift occurs in the flow in the furnace, the residence time in the furnace becomes shorter on the short path flow 50 side, and the amount of unburned matter discharged increases significantly.

This phenomenon of drifting in the reactor was confirmed through a so-called visualization experiment conducted by the inventors, in which water mixed with tracer particles was flowed through a plastic model and observed.
The cause is a slight difference in the flow rate and operation conditions of the burners 13 placed on the front wall 2 side and the rear wall 3 side, or a difference in the flow rate and operation between the multiple front wall burners 13a and rear wall burners 13b, respectively. This is because slight differences in conditions are facilitated by mutual interference between the jets or between the jets and the wall.

[Problem to be solved by the invention]

An object of the present invention is to provide a U-shaped combustion furnace that can solve the problems of the prior art described above, eliminate drifting and short paths in the furnace, maintain a good combustion state, and reduce discharged unburned matter. It's about doing.

[Means to solve the problem]

The above object is achieved by providing a dividing wall that partitions the hopper space at the bottom of the furnace into a front wall and a rear wall.

That is, the present invention provides front and rear bottom walls that slope inward to form a hopper, a vertical abdominal wall that continues above both bottom walls, and a horizontal or oblique wall that is connected to the top of the abdominal wall. A furnace front wall and a furnace rear wall each consisting of a shoulder wall extending upward, a furnace neck wall connected above the shoulder wall, and a ceiling wall connected to the furnace neck wall; In a U-shaped combustion furnace, the hopper section at the bottom of the furnace is equipped with left and right side walls that connect the walls to surround the furnace space, and burners that are installed on the front and rear shoulder walls and inject fuel toward the hopper section. It is characterized by the provision of a dividing wall that separates the front and rear.

[Effect]

The jets from the front and rear wall burners that are injected toward the hopper space at the bottom of the furnace are blocked by the dividing wall so that they do not interfere with each other, and they quickly turn around and rise along the dividing wall, resulting in uneven flow within the furnace. Phenomena that adversely affect combustion, such as short passes, can be prevented.

〔Example〕

FIG. 1 is a cross-sectional view of a U-shaped combustion furnace showing an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 3 is a jet flow shown in FIG. FIG. 4 is a detailed view of the flat solid wall of FIG. In the figure, the furnace space 1 is
An abdominal part (b) and a shoulder part (c) having a front wall 2, a rear wall 3, a left side wall 4, and a right side wall 5, and a hopper part (a) having an inclined front hearth bottom wall 7a and a rear hearth bottom wall 7b. and a ceiling wall 6. Shoulders 10 of the front wall 2 and rear wall 3.
Burners 13 are arranged in opposing positions in each of the burners 11 . A flat solid wall 22 is installed at the bottom of the furnace space 1, that is, the hopper section (A), and the hopper section (A) is divided into a front hearth bottom space 23a and a rear hearth bottom space 23b.

A discharge port 15 for ash, slag, unburned materials, etc. is provided at the bottom of the hopper section (a). Fuel 17 is on the shoulder (c)
It is supplied to the burner 13 provided in the. Air is in the abdomen (
(b) After being supplied to the wind box 12 provided on the shoulder (c), it is blown into the furnace through the air ports 14 provided on the burner 13, the front wall abdomen 8, and the rear wall abdomen 9. There is a furnace outlet 21 in the upper part of the furnace, that is, near the ceiling wall 6, and a heat exchanger 16, which mainly uses convection heat transfer, is placed to recover heat.

As a method of providing the flat solid wall 22 in the furnace hopper section (a), as shown in FIG. 4, a support member 28 is provided between the front furnace bottom wall 7a and the rear furnace bottom wall 7b, and a refractory brick There is a way to accumulate 29.

At this time, it is necessary that the outlet 30 communicates with the outlet 15 shown in FIG.

The fuel 17 and air 18 supplied from the burners 13 on the front wall shoulder 10 and the rear wall shoulder 11 of the furnace pass through the solid wall 22 in the form of a fuel plate.
Since it is composed of the support member 28 and the refractory bricks 29, its installation is relatively simple.

FIG. 5 is a sectional view of a hopper portion of a U-shaped combustion furnace according to another embodiment of the present invention. In this embodiment, a flat solid wall 22 is cooled by air blown in through a duct 31 and a slit 43, or by a cooling gas 32 such as combustion exhaust gas. Since the flow 33 of the cooling gas 32 cools the surface of the flat solid wall 22 while rising, it helps reverse and rise the burner jet flow, and the surface of the flat solid wall 22 becomes hot and slag etc. Prevents adhesion,
Keep the outlet 15 or 30 healthy. Furthermore, exhaust gas recirculation methods used to improve combustion and control steam temperature
A flat solid wall 22 is applied, which can produce effects such as guiding exhaust gas to the center of the furnace.

FIG. 6 is a structural diagram of a flat solid wall according to yet another embodiment. The flat solid wall 22 is passed through the lower header 34, the upper header 35, and the plurality of pipes 36 into the fuel/air mixture 19, and the direction toward the front furnace bottom wall 7a and the rear furnace bottom wall 7b,
In other words, it is ejected downward. Therefore, the jet is the third
As shown in the figure, the flows are initially downward flows 24a and 24b, which are reversed near the front hearth bottom space 23a and rear hearth bottom space 23b, respectively, and become upward flows 25a and 25b, passing through the furnace neck (d) and passing through the furnace. It is discharged from the outlet 21.

As mentioned above, the jets from the burners 13 on the front wall 2 and rear wall 3 are reversed near the furnace bottom spaces 23a and 23b;
At this time, since the flat solid wall 22 exists, the two jets do not interfere with each other. Therefore, even if there is an imbalance in the flow rates of the two jets or other factors, this will not be exacerbated to produce the uneven flow or seat path flow 50 as shown in FIG. 18. It was confirmed in the above-mentioned visible wildflower experiment that the furnace having the structure shown in FIG. 1 exhibits a U-shaped flow state with no drift as shown in FIG.

Since the flat solid wall 22 can be installed without changing the shape of the conventional furnace, drifting can be prevented with simple modification work. In particular, it has a flat configuration as shown in FIG. 4, and employs an internal cooling structure in which a cooling medium 37 is supplied to a lower header 34 and a cooling medium 38 is extracted from an upper header 35. The plurality of tubes 36 may have a membrane structure in which tubes are connected with fins, or may simply be arranged so that the tubes 36 are in contact with each other. Moreover, FIG. 7 is a structural diagram of a flat solid wall according to still another embodiment, and FIG.
It is a sectional view taken along the line B, and the bottom side of the furnace may be a membrane part (E) and the upper part thereof may be a screen part (E). When this structure is adopted, the flat solid wall 22 can be suspended and supported from the upper part of the furnace (shoulder (C), neck (D), or ceiling wall 6), so its strength can be easily designed. Become.

In the examples shown in FIGS. 6 and 7, it is possible to recover heat from the cooling medium 37 used for cooling, and a separate system for this purpose may be added.

FIG. 9 is a dimensional explanatory diagram of the flat solid wall in the present invention, and shows the burner jet central axis 41 from at least the lowest part of the furnace.
It is preferable to set the distance to the intersection 51 of a and 41b to Ho, or preferably to Hl, which is longer than that.

FIG. 10 is a sectional view of a U-shaped combustion furnace according to still another embodiment, in which a flat solid wall 2 is provided in the bottom hopper space (A).
2, a triangular prism-like structure 42 is arranged.

That is, whether the triangular bottom surface of the triangular prism structure 42 touches or is supported by the left and right boiler side walls 4.5;
It will be located nearby. Also, it is usually placed horizontally, with one of the vertices of the triangular base being above the other two vertices. By placing the triangular prism-shaped structure 42 at the hearth bottom in this positional relationship, the space of the hearth bottom hopper portion (a) is formed into a W-shape when viewed from the direction of the side wall 4.5. Front hearth bottom space 23a and rear hearth bottom space 23
It is divided into b. The outlet for slag, ash, unburned matter, etc.
15 al,, 15. There are two locations b. As shown in Fig. 11, the flow inside the furnace is as follows:
This is similar to the case where No. 2 is installed, and uneven flow of the gas flow can be prevented. In this embodiment, the height of the furnace can be reduced compared to a hopper structure with one discharge port, and the construction cost can be reduced.

The triangular prism-like structure 42 is the flat solid wall 22 described above.
As in the case of , it can be constructed of refractory or cooling walls. As shown in FIG. 12, cooling gas 32 is jetted out from ducts 31 and slits 43 provided on the front furnace bottom wall 7a and the rear furnace bottom wall 7b, and the surface of the triangular prism-shaped structure 42 is cooled by the cooling gas flow 33. It is also possible to prevent the adhesion of slag, etc. and the clogging of the discharge ports 15a and 15b.

FIG. 13 shows an example in which the triangular prism-shaped structure 42 is formed with an internal cooling wall, and the lower headers 34a and 34b are provided with a cooling medium 37.
is supplied, rises along the membrane wall 44, and is extracted from the upper header 35 as a cooling medium. Needless to say, it is possible to recover heat from the extracted cooling medium 38. The membrane wall 44 connects the lower ladders 34a, 34b and the upper header 35, but it is not necessary to adhere to the membrane wall 44 (as long as a channel through which the cooling medium 37 flows is formed). It is preferable to cover the surface of the header 35 and, if necessary, the membrane wall 44 with a refractory material 53 as shown in FIG. 14. This can prevent the headers from being exposed to high temperatures and deteriorating.

In FIG. 15, water-cooled walls with membrane walls 46a and 46b at the bottom and screen tubes 47a and 47b at the top are crossed to form a central hearth bottom wall 45, creating a W-shaped space. The upper part of the central hearth bottom wall 45 is integrated with the front wall abdomen 8 and the rear wall abdomen 9. With this structure, cooling water flows smoothly within the tubes, and there is no risk of tube burnout due to thermal load imbalance.

〔Effect of the invention〕

According to the present invention, since the structure that partitions the bottom hopper space of the U-shaped combustion furnace into the front wall side and the rear wall side is provided, the burners on the front wall and the rear wall are directed toward the bottom hopper portion, respectively. The injected jets reverse and rise without interfering with each other, each exhibiting a U-shaped flow. Therefore, the front wall side,
The necessary residence time in the furnace can be secured without short-passing any of the burner jets on the rear wall side, so even when using flame-retardant fuel, emissions of unburned substances are small and good combustion conditions can be maintained. There are many effects that can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a U-shaped combustion furnace showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 3 is a flow diagram in FIG. 1. , FIG. 4 is a detailed view of the flat solid wall of FIG. 1, FIG. 5 is a sectional view of the hopper portion of a U-shaped combustion furnace showing another embodiment of the present invention, and FIGS. 6 and 7 are a detailed view of the flat solid wall of FIG. ,
FIG. 8 is a cross-sectional view taken along the line B-B in FIG. Fig. 10 is a sectional view of a U-shaped combustion furnace showing still another embodiment of the present invention, Fig. 11 is a flow diagram in Fig. 10, and Fig. 12 is a further embodiment of the present invention. FIG. 13 is a sectional view of a hopper portion of a U-shaped combustion furnace showing another embodiment of the present invention, and FIG. 14 is a planar solid wall structure diagram of a U-shaped combustion furnace showing still another embodiment of the present invention. An enlarged sectional view of the upper header in FIG. 13,
FIG. 15 is a sectional view of a flat solid wall of a U-shaped combustion furnace showing still another embodiment of the present invention, FIG. 16 is a sectional view of a conventional U-shaped combustion furnace, and FIG. 17 is a sectional view of a U-shaped combustion furnace of the prior art. C-C in Figure 16
The cross-sectional view taken along the line, FIG. 18, is a flow diagram in FIG. 16. 1...Furnace space, 2...Front wall, 3...Rear wall, 4...
...Left wall, 5...Right wall, 6...Ceiling wall, 7a...
... Front hearth bottom wall, 7b... Rear hearth bottom wall, 8... Front wall abdominal wall, 9... Rear wall abdominal wall, 10... Front wall shoulder wall,
11... Rear wall shoulder wall, 12... Bend box,
13.13a, 13b...burner, 14...airport, 15.15a, 15b...discharge port, 16...
Heat exchanger, 17...Fuel, 18...Air, 19...
- Fuel air mixture, 20... Combustion gas, 21... Furnace outlet, 22... Flat solid wall (dividing wall), 23a.
... Front hearth bottom space, 23b... Rear hearth bottom space, 24a
, 24 b...downward flow, 25a, 25 b -...
Upward flow, 26a, 26b', 27a, 27b...
Whirlpool, 2nd...Supporting member, 29 Firebrick, 30...
Discharge port, 31... Duct, 32... Cooling gas, 33
...Cooling gas flow, 34.34a, 34b...Lower header, 35...Upper header, 37.38...Cooling medium, 39...Fin, 40...Gap, 41a, 41
b... Burner jet center axis, 42... Triangular prism structure, 43... Slit, 44... Membrane wall, 45
...Central hearth bottom wall, 46a, 46b...membrane part, 47a, 47b...screen part. Applicant Babcock Hitachi Co., Ltd. Agent Patent Attorney Takenaga Kawakita Figure 1] Two-person furnace space 2: Front wall 3: Rear wall 4: Left wall 5: Right wall 6: Ceiling wall] 3: Burner 17: Fuel 8: Air] 9': Fuel-air mixture 202 Fuel gas 22: Flat solid wall Figure 2, '11 100 to 100 Kuraku no B Shitsu! - J) Figure 17 Figure 18

Claims (1)

[Claims] (1) Front and rear hearth bottom walls that slope inward to form a hopper, a vertical abdominal wall that continues above both hearth bottom walls, and a horizontal or obliquely upwardly extending wall that is connected to the top of the abdominal wall. A furnace front wall and a furnace rear wall, which are composed of a shoulder wall, a furnace neck wall connected above the shoulder wall, and a ceiling wall connected to the furnace neck wall, and the front and rear walls of the furnace are connected. A dividing wall that partitions a hopper section below the furnace into front and rear parts in a U-shaped combustion furnace that is provided with left and right side walls that surround the furnace space and burners that are installed on the front and rear shoulder walls and inject fuel toward the hopper section. A U-shaped combustion furnace characterized by being equipped with.