JPH0245766B2 - KOTAINENRYOTAKIRO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a technique for saving heat in the lower part of a coal-fired furnace. In particular, the present invention relates to a technique for saving energy by reflecting incident radiant heat from the bottom of a coal-fired furnace back to the lower part of the steam generating section of the furnace.

Conventional technology As part of the energy problems we are currently facing,
There has been intensive planning for coal-fired furnaces and oil-fired and gas-fired furnaces that can be modified to burn coal. A coal-fired furnace has a sloping side transition called a coutant transition at its bottom to cool and collect solid residue from the combustion zone. In particular, this lateral slope transition is in the form of a funnel whose sides are inclined at an angle of 50 to 60 degrees to the horizontal, and whose bottom is 5 cm (2 cm).
The slot can be as wide as 10 cm (4 inches) or 10 cm (4 inches) wide. Below this slot is water stored in an ash hopper that receives hot solid fuel residue and collects it for later removal.

Although the tubes forming the water tube walls extend down the side of the side slope transition, this side slope transition is below the coal combustion section of the furnace, thus reducing the net volume of the combustion chamber. I'm letting you do it. Furthermore, the radiant heat that enters from above the side slope transition portion is thrown into the water that accumulates below, and is not utilized for steam generation.

When converting an oil-fired or gas-fired furnace to a coal-fired furnace, the inherent losses caused by this side slope transition will be experienced in the converted furnace as well. Whether the furnace was originally designed as a coal-fired furnace or a retrofitted oil-fired or gas-fired furnace, the volume of the side slope transitions can be reduced to make better use of the combustion chamber volume. Delicious.

More specifically, one of the major problems encountered when converting industrial and general purpose oil-fired and gas-fired boilers with large top-supported vertical furnaces to coal-fired boilers is the significant loss of furnace volume. This loss is due to the fact that the bottom of a conventional couplant hopper must be added to remove the ash associated with coal combustion. The reduction in furnace volume in this case is
This is the limiting factor in determining the maximum boiler volume when retrofitting and firing coal. Furnaces originally designed to fire coal, as well as refurbished oil-fired and gas-fired furnaces, require a construction that improves this, even when furnace volume is the limiting factor. It is required to be able to obtain boiler capacity.

Furthermore, for the currently used ash hopper, it is hoped that an effective structure will be developed to reduce the waste heat of radiation that enters the ash hopper from the furnace and is absorbed by and heats the waste water in the ash hopper. has been done. There is also a need to eliminate or significantly reduce the ash hopper water cooling and recirculation system used to maintain the ash hopper water temperature below the boiling point.

DISCLOSURE OF THE INVENTION The present invention provides a material to the water surface of the water accumulated in the ash hopper immediately below the couplant transition section of a coal-fired furnace, thereby reflecting the incident combustion heat back to the steam generating section of the furnace. There is a particular thing.

The present invention further provides that the reflective material on the top surface of the water in the ash hopper allows solid residues of coal combustion to pass into the water without resulting in substantial loss of this reflective material from the water surface. It is in.

Other objects, advantages and features of the invention will become apparent from the description below.

DETAILED DESCRIPTION OF THE INVENTION Terminology and Techniques It is unnecessary to list various terms related to conventional coal-fired, gas-fired, and oil-fired furnaces or to describe the technology associated therewith.
These terms are so well known that I do not think it is necessary to explain them again here. Additionally, the water pipe walls of the furnace, the burner system that creates the combustion zone inside the water pipe wall, and the general construction of the dry bottom of the couplant transition section that controls the collection of solid residues from coal combustion are all familiar in the industry. It is. It should be noted, however, that water is collected below the lower opening of the coupant transition and receives the hot solid residue continuously produced by the combustion of the solid fuel above the coupant transition. The lower opening of this transition is a slot, which is made as narrow as possible to direct the falling residue into the pool of water and to drain it periodically or continuously. It is scraped out at a single point on the chain of equipment.

As it is exposed to the incident radiation of combustion in the furnace, this water heats up with waste heat. Therefore, it is necessary to provide a cooling system to prevent this water from boiling.
The present invention significantly reduces the temperature of this water and significantly reduces the strain on the cooling system required for this water. The invention is embodied in an apparatus for returning this incident radiation back into the furnace above the transition and for heating the water flowing through the tubes in the water tube wall, effectively producing steam. The effectiveness of the invention allows the narrow slot of the transition to be widened, thereby reducing the height of the transition and widening the full width of the water tube wall, thereby shifting the burner downwards. The effective furnace volume for combustion can be increased.

Furnace Bottom Arrangement Figure 1 shows only the lower part of a general-purpose furnace or boiler. The combustion chamber 1 is a volume defined within the water pipe wall 2 of the furnace. The burner 3 is illustrated to the extent that it can be described as burning solid fuel within the combustion chamber 1. It is well known that heat is transferred to the water within the water pipe wall 2 by convection and radiation, and no further explanation is necessary.

The furnace may be originally designed as a coal-fired furnace, or it may be an oil-fired or gas-fired furnace that has been converted to a coal-fired furnace. In any case, the combustion of the solid fuel produces a solid residue, which must fall to the bottom and be guided into the funnel-shaped transition section 5. The lower part of the transition section 5 ends in an opening 6. Water 7 is stored directly below this opening 6. Of course, the solid residues of combustion are guided by the inclined walls of the transition section 5 and fall into a relatively narrow area below the opening 6. The solid residue thus collected is removed continuously or periodically by a system which does not need to be detailed here.

Invention According to the invention, a material is applied to the surface of the collected water 7, which causes it to remain on this surface and by which the incident radiation is reflected upwards again. Proper selection of the material 10 results in efficient reflection of a significant amount of the incident radiation. Without this material, this amount of incident radiation would heat the water 7 and be wasted as waste heat. This material is maintained at the surface of the water, but the solid residue must fall through it into the water.
Furthermore, a substantial portion of this material must not be blown away from the water surface along with solid residues.

This essential material 10 embodying the invention is a group of small diameter spheres with a specific gravity of 1 or less. In other words, this group of small diameter spheres must float on the surface of the water 7. Of course, this material must reflect a significant amount of the incident radiation.

According to a preferred embodiment of the invention, this material is a hollow sphere made of metal, such as aluminum.

A collection of sufficiently small spheres of metal such as aluminum will easily pass through solid residue;
Again, an effective reflective surface for incident radiation can be formed. However, a material 10 made of small spheres of metal, for example aluminum, floats on the surface of the water 7, can form a reflective surface, and can pass solid residues into the water 7 satisfactorily. FIG. 2 is an enlarged view showing the reflective material 10 positioned on the surface of water 7. As shown in FIG.

The immediate impact of the present invention on the design of coal-fired furnaces is that the dry bottom height of this furnace is reduced. There is no need for the outlet from the funnel-shaped coupant transition to be narrowed to 5 cm (2 inches) to 10 cm (4 inches).
Traditionally, reducing the area of this section has been essential to limit waste heat due to incident radiation from the combustion zone above. However, since the present invention provides an effective reflective surface, a larger area of the material covering the collected water may be exposed. This is because this incident radiation is reflected back into the combustion region. There is no need to describe the fact that this incident radiation is effectively reflected. The structure of the present invention is simple, and it is clear that the reflected radiation can increase the efficiency of heating the pipe on the water pipe wall and efficiently generate steam. All that is required for embodiments of the invention is a heat reflective, solid residue permeable material maintained on the surface of the water as described above.

Although the present invention has been described above in detail with reference to its preferred embodiment, it is to be understood that the present invention is not limited to this specific embodiment, and that many changes and modifications can be made without departing from the spirit of the present invention. .

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view of a furnace to which the present invention is applied;
The figure is an enlarged sectional view of the surface of water stored in the ash hopper. 1... Combustion chamber, 2... Water tube wall, 3... Burner,
5...Transition part, 6...Opening, 7...Water, 10...
material.

Claims (1)

[Claims] 1. A combustion section defined by a water pipe wall, a burner installed through the water pipe wall of this combustion section to burn solid fuel, and an outlet installed below the combustion section for receiving combustion residue of the solid fuel. a lateral slope transition terminating in the slope; an ash sump located below the exit slope; water stored in the ash sump with a water surface below the exit slope; A solid fuel-fired furnace comprising a group of small-diameter spheres made of a material provided on the surface of water and reflecting incident radiation from the combustion section back to the combustion section and having a specific gravity that floats on water.