JP2016023865A - Stoker furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stoker furnace that enhances combustion efficiency of a soil fuel moving on a fire grate in a combustion furnace.SOLUTION: In a stoker furnace, a stationary fire grate 26b and a movable fire grate 26a partially mounted on the stationary fire grate 26b are alternately arranged; the movable fire grate 26a can oscillate along the upper surface of the stationary fire grate 26b; a solid fuel 12 is combusted while extruded on the stationary fire grate 26b and the movable fire grate 26a. When the height of the movable fire grate 26a is defined as H2, and the height of the solid fuel 12 moving on the movable fire grate 26a is defined as H1, the following relation is satisfied: H2>H1.SELECTED DRAWING: Figure 2

Description

  The present invention particularly relates to a stoker furnace that burns while moving a solid fuel on a grate in the combustion furnace.

  A stoker furnace that burns while stirring and transporting solid fuel by the movement of a grate (stalker) installed in the combustion furnace is used for boilers and the like because it can be operated continuously with the combustion status kept constant ( For example, disclosed in Patent Document 1).

  Stoker furnaces are used in particular for the combustion of solid fuels. The solid fuel is not made into a fine powder state even with the same fuel, but the absolute value of the size of the fuel differs depending on the volatile content and moisture factors of the fuel. A typical stoker furnace is suitable for burning a fuel having a particle size of 6 mm to 40 mm. Inside the stoker furnace, the fuel supplied from the supply port and stacked on the grate is gradually pushed out toward the ash discharge port according to the moving speed of the grate while burning. The fuel that does not burn on the grate is finally pushed out of the grate and collected as ash from the ash outlet.

JP 11-51359 A

  As combustion conditions for solid fuel, it is indispensable that particles and particles maintain an appropriate space when being stacked on a grate and that combustion air easily passes through. However, in actuality, fuels may be stacked together in close contact or in close contact with each other, or fine powder in the fuel may enter the space of coarse particles, and the air resistance may be significantly increased. As a result, the combustion air is insufficient, and the ideal combustion rate is fast, and it is difficult to say that the combustion state is stable. The slow combustion rate means that the amount of fuel that can be burned per hour is small, and thus the amount of heat generated is also small. In this case, the apparatus must be enlarged and compensated.

  For this reason, there is a pulverized coal combustion facility in which the solid fuel is pulverized and the specific surface area in contact with air is remarkably increased to greatly increase the combustion rate. However, pulverizing and burning all the solid fuel requires a raw material cost and lacks technical and economical rationality.

  Therefore, in view of the above-mentioned problems of the prior art, an object of the present invention is to provide a stoker furnace that improves the combustion efficiency of solid fuel that moves on a grate in the combustion furnace.

  As a first means for solving the above-mentioned problem, a fixed grate and a movable grate partially placed on the fixed grate are alternately arranged to move the movable grate along the upper surface of the fixed grate. In a stoker furnace that enables the grate to swing and burns while extruding solid fuel on the fixed grate and the movable grate, the height of the movable grate is H2, and the grate moves over the movable grate An object of the present invention is to provide a stoker furnace characterized by satisfying the relationship of H2> H1, where H1 is the height of the solid fuel.

  As a second means for solving the above-mentioned problem, in the first means, the movable grate is perpendicular to the upper surface of the fixed grate on a side part partially placed on the fixed grate. To provide a stoker furnace characterized in that an inclined surface inclined by 10 degrees or more is provided on the fixed grate side where a part of the upper end is placed from the lower end of the side portion toward the upper end with respect to the direction. It is an object.

  As a third means for solving the above-mentioned problem, in the first or second means, the movable grate has the inclined surface at the lower end of the side part partially placed on the fixed grate. An object of the present invention is to provide a stoker furnace characterized in that a ridge that protrudes on the fixed grate while being curved is formed.

  As a fourth means for solving the above problem, in any one of the first to third means, the height of the movable grate is H2, and the maximum particle size of the solid fuel is Dp100. The object of the present invention is to provide a stoker furnace characterized by satisfying the relationship of H2 / Dp100> 1.

  As a fifth means for solving the above-mentioned problem, the movable grate according to any one of the first to fourth means is formed in a direction intersecting the moving direction of the solid fuel, It aims at providing the stoker furnace characterized by having formed one or more places between fixed grate.

  According to the configuration of the present invention as described above, the solid fuel extruded on the grate can be agitated and reversed by dropping, thereby increasing the exposed surface area of the solid fuel and complete burning in a short time. .

This makes it possible to reduce the volume of the combustion chamber when the combustion amount is constant, to reduce the size of the entire apparatus, and to reduce the capital investment cost.
Further, when the volume of the combustion chamber is constant, the amount of combustion can be increased. For example, a combustion furnace having a large processing capacity can be constructed even if the apparatus configuration is small.

  In addition, when the movable grate swings (advances and retreats) on the fixed grate, the solid fuel moves on the inclined surface of the movable grate so as to dig up the solid fuel. And a new oxidation-exposed surface can be formed. This corresponds to a reduction in the combustion particle size, and the combustion time can be shortened.

  Since the movable grate is formed in the direction intersecting the moving direction of the solid fuel and at least one place is formed between the fixed grate, the solid fuel supplied to the combustion furnace is stirred and inverted one or more times. And can increase the exposed surface area of the solid fuel and burn it completely in a short time.

It is the schematic which shows the structure of the stoker furnace of this invention. It is explanatory drawing of the height of a movable grate. It is explanatory drawing of the inclined surface of a movable grate. It is a graph which shows the relationship between combustion time and particle diameter. It is a graph which shows the relationship between combustion time and inversion number.

  Embodiments of the stoker furnace of the present invention will be described below in detail with reference to the accompanying drawings.

[Stoker furnace 10]
FIG. 1 is a schematic view showing the configuration of the stoker furnace of the present invention. As shown in the figure, the stoker furnace 10 of the present invention mainly has a combustion furnace 20 for a solid fuel 12 and a flue 36 for combustion gas generated by the combustion of the solid fuel 12.

  The combustion furnace 20 is a furnace that generates biomass by heating biomass and various solid fuels 12 to a predetermined temperature.

  The combustion furnace 20 includes a supply port 23 for the solid fuel 12 on the side surface, an ignition burner 24a for igniting the solid fuel 12 in the furnace, a temperature raising burner 24b for heating and burning the solid fuel 12 at a predetermined temperature, and generated combustion gas. Is provided in the combustion furnace 20, and a stoker 26, a primary air fan 25a, and an ash discharge port 28 are formed below.

The stalker 26 has a configuration in which movable grate 26a and fixed grate 26b are alternately formed.
The fixed grate 26b is a block or plate on which the solid fuel 12 can be placed on the upper surface, and a plurality of fixed grate 26b are fixed to the lower surface of the combustion furnace 20 via a rotating shaft. The fixed grate 26b shown in FIG. 1 is formed flat on the floor side of the combustion furnace 20. The fixed grate 26b is attached with a predetermined interval between the adjacent fixed grate 26b.

The movable grate 26a is attached between the fixed grate 26b. The movable grate 26a is arranged so that one end on the ash discharge port 28 side is on the fixed grate 26b (the ash discharge port 28 side), and the fixed grate 26b (the supply port 23) is placed on the other end on the supply port 23 side. Side) is placed. The movable grate 26a is a block or plate on which the solid fuel 12 can be placed on the upper surface, like the fixed grate 26b. Each movable grate 26a is connected to a swing rod 27 provided below via a rotating shaft. The rocking rod 27 is attached along the direction in which the longitudinal direction is from the supply port 23 toward the ash discharge port 28 (moving direction of the solid fuel 12 (arrow A)). The rocking rod 27 is configured to be movable back and forth along the moving direction (arrow A) of the solid fuel 12, and the movable grate 26a to be connected is also fixedly fired along the moving direction (arrow A) of the solid fuel 12. It moves forward and backward on the lattice 26b. The size of the fixed grate and the movable grate can be set to, for example, a length of 300 mm in the longitudinal direction, a length of 50 mm in the width direction, and a thickness of 20 mm to 50 mm.
A primary air fan 25 a is provided below the stalker 26. The primary air fan 25a is a fan that introduces combustion air to the upper side of the combustion furnace through the movable grate and the fixed grate from the lower side of the combustion furnace.

  In the stalker 26 having such a configuration, the fixed grate 26b and the movable grate 26a are alternately arranged on the floor surface in the combustion furnace 20, and when the swing rod 27 moves forward and backward, the stalker 26 is placed on the stalker 26 from the supply port 23. Is fed from the upper surface of the movable grate 26a to the upper surface of the adjacent fixed grate 26b. Further, it is extruded from the upper surface of the fixed grate 26b to the upper surface of the adjacent movable grate 26a. While repeating these steps, the solid fuel 12 moves on the movable grate 26a and the fixed grate 26b from the wall surface side provided with the supply port 23 toward the wall surface side provided with the opposing ash discharge port 28. To do.

  In the combustion process of the solid fuel 12 in the stalker furnace 10, volatile components such as methane gas in the solid fuel 12 are generated, and the heat ignited by the volatile components ignites and burns fixed carbon. The time until the combustion is completed is considered to be proportional to the specific surface area of the particle diameter, assuming that air is continuously supplied. FIG. 4 is a graph showing the relationship between combustion time and particle size. The graph shows the relationship between the particle diameter (mm: horizontal axis) and the combustion time (second: vertical axis) when biomass and various solid fuels are heated and burned at a combustion temperature of 800 to 900 degrees. As shown in the graph, it can be seen that the combustion time increases as the particle size increases.

This state is ideal based on the image of a single particle diameter. In combustion in a state where solid fuel is laminated like a stoker furnace, ash is generated by burning on the surface of the laminated layer. This ash is considered to inhibit the flow of air and the generation of volatile matter from below.
If a new oxidation-exposed surface can be formed by inverting and stirring the laminated solid fuel that has fallen into such a state, the process of generating volatile matter, ignition, and ignition can be easily repeated. it can.
In general, when the cube is divided into 1/2 and 1/3, the new exposed areas excluding the bottom surface are 1.4 times and 1.8 times, respectively, before the division.

Here, assuming that the maximum particle diameter (Dp100) is 40 mm, the 50% average particle diameter (Dp50) corresponds to about 15 mm from the particle size distribution, assuming that the particles are particles. If the idea of specific surface area and combustion time is combined with this equivalent particle diameter, the increase in specific surface area can be replaced by the size of the combustion particles.
That is, Dp50 = 15 mm with the cube set to 0 inversions.
If the one inverted is equivalent to 1/2 split,
Average particle diameter Dp50 = 15 × (1 / 1.4) = 10.7 mm
It becomes.
In addition, if it is equivalent to 1/3 division of what is inverted twice,
Average particle diameter Dp50 = 15 × (1 / 1.8) = 8.3 mm
It becomes.

If the correlation between the particle size and the combustion time of the graph shown in FIG. 4 is added to the calculation result, the graph shown in FIG. 5 is obtained. The horizontal axis of the graph represents the number of inversions (number corresponding to division), and the vertical axis represents the combustion time (seconds).
As shown in the graph, when the inversion number is 1, the combustion time is 310 seconds, and the combustion time can be shortened by about 23% with respect to the combustion time 400 seconds before the inversion.
When the inversion number is 2, the combustion time is 270 seconds, and the combustion time can be shortened by about 33% with respect to the combustion time 400 seconds before the inversion. Thus, it can be seen that forming the exposed surface area corresponds to a decrease in the combustion particle size, and the combustion time is shortened.

FIG. 2 is an explanatory diagram of the height of the movable grate. The stoker furnace 10 of the present invention has a relationship of H2> H1, where the height of the movable grate 26a is H2, and the height of the solid fuel 12 moving on the movable grate 26a (the thickness of the stack) is H1. It is set to satisfy.
The stoker furnace 10 of the present invention can reduce the height of the solid fuel 12 by increasing the swing speed of the movable grate 26a. On the other hand, the solid fuel 12 can be made thicker by slowing the rocking speed of the movable grate 26a. In addition, the swinging of the movable grate 26a uses one cycle of the feed, stop, and return processes, but the height of the solid fuel 12 can be reduced by shortening the stop time of one cycle. Such a swing speed of the movable grate 26a can be controlled so as to satisfy the relationship of H2> H1.

  By making the movable grate 26a higher than the height of the solid fuel 12, when the solid fuel 12 pushed onto the fixed grate 26b falls downward from the movable grate 26a, stirring and reversal action can be added. And a new oxidation-exposed surface can be formed. This corresponds to a reduction in the combustion particle size, and the combustion time can be shortened.

  FIG. 3 is an explanatory diagram of an inclined surface of the movable grate. As shown in (1), the movable grate 26a of the present invention has a side part partially placed on the fixed grate 26b on the ash discharge port 28 side, and is perpendicular to the orthogonal direction of the upper surface of the fixed grate 26b. An inclined surface 29 inclined by 10 degrees or more is provided on the fixed grate 26b side where a part of the upper end is placed from the lower end of the side portion toward the upper end. Since such an inclined surface 29 has an upper end inclined more to the fixed grate 26b side on the ash discharge port 28 side than the lower end, when the movable grate 26a swings (advances and retreats) on the fixed grate 26b. Further, since the solid fuel 12 moves on the fixed grate 26b so as to dig up, the solid fuel 12 can be agitated and inverted, and a new oxidation-exposed surface can be formed. This corresponds to a reduction in the combustion particle size, and the combustion time can be shortened.

  Moreover, as shown in (2), the movable grate 26a is a flange that protrudes on the fixed grate 26b while curving from the inclined surface 29 at the lower end of the side part partially placed on the fixed grate 26b. 30 is formed. Since such a flange 30 is curved so that the upper end rises in a tapered shape from the lower side to the upper side, when the movable grate 26a moves forward and backward on the fixed grate 26b, the fixed grate 26b Since the solid fuel 12 moves so as to dig up, the agitation or inversion action can be imparted to the solid fuel 12, and a new oxidation exposure surface can be formed. This corresponds to a reduction in the combustion particle size, and the combustion time can be shortened.

  In the present invention, the height of the movable grate 26a is set to H2, and the maximum particle diameter of the solid fuel 12 is set to Dp100, so that the relationship of H2 / Dp100> 1 is satisfied. When the maximum particle diameter Dp100 of the solid fuel is lower than the height of the movable grate 26a, the agitation and inversion action are added when the solid fuel 12 pushed onto the fixed grate 26b falls downward from the movable grate 26a. New oxidation exposed surfaces can be formed. This corresponds to a reduction in the combustion particle size, and the combustion time can be shortened.

  The flue 36 is provided in the upper part of the combustion furnace. The flue 36 is a duct that can supply the combustion gas generated inside the combustion furnace 20 from the combustion furnace 20 to a subsequent boiler or the like.

[Action]
The operation of the stoker furnace 10 of the present invention having the above configuration will be described below.
After ignition by the ignition burner 24a of the combustion furnace 20, the inside of the furnace is heated by the temperature raising burner 24b. Combustion air is introduced into the furnace from below the combustion furnace 20 by the primary air fan 25a. Then, the solid fuel 12 is supplied from the supply port 23 of the combustion furnace 20. The solid fuel 12 supplied from the supply port 23 onto the stoker 26 is heated and burned while being secondarily moved on the stoker 26 to generate combustion gas. The combustion gas generated in the furnace is agitated inside the combustion furnace 20 by the secondary air fan 25b, and is introduced from the combustion furnace 20 into the flue 36 by an exhaust fan (not shown).

  The stoker furnace 10 of the present invention has a relationship of H2> H1, where the height of the movable grate 26a is H2, and the height of the solid fuel 12 moving on the movable grate 26a (the thickness of the stack) is H1. It is set to satisfy. Further, as shown in the figure, the movable grate 26a according to the present invention is formed on the side part partially placed on the fixed grate 26b on the ash discharge port 28 side with respect to the orthogonal direction of the upper surface of the fixed grate 26b. An inclined surface 29 inclined by 10 degrees or more is provided on the fixed grate 26b side where a part of the upper end is placed from the lower end of the side portion toward the upper end. Moreover, the movable grate 26a forms the collar part 30 which protrudes on the fixed grate 26b, curving from the inclined surface 29, in the lower end of the side part partially mounted on the fixed grate 26b. In the present invention, the height of the movable grate 26a is set to H2, and the maximum particle diameter of the solid fuel 12 is set to Dp100, so that the relationship of H2 / Dp100> 1 is satisfied. The movable grate 26a is formed across the direction perpendicular to the moving direction of the solid fuel 12, and is formed at one or more places between the fixed grate 26b.

For this reason, when the solid fuel 12 pushed out onto the fixed grate 26b falls downward from the movable grate 26a, it is possible to add agitation and inversion action and form a new oxidation exposure surface. This corresponds to a reduction in the combustion particle size, and the combustion time can be shortened.
Further, when the movable grate 26a moves forward and backward on the fixed grate 26b, it moves so as to dig up the solid fuel 12 on the fixed grate 26b, so that the solid fuel 12 can be agitated or reversed. New oxidation exposed surfaces can be formed. This corresponds to a reduction in the combustion particle size, and the combustion time can be shortened.

  INDUSTRIAL APPLICABILITY The present invention can be used industrially effectively in the fields of boilers that employ a stoker combustion system, incinerators that incinerate solid fuel, gasification furnaces, melting furnaces, and the like.

10 ......... Stoker furnace, 12 ......... Solid fuel, 20 ......... Combustion furnace, 23 ......... Supply port, 24a ......... Ignition burner, 24b ......... Temperature burner, 25a ......... Primary air Fan, 25b ......... Secondary air fan, 26 ......... Stoker, 26a ......... Moveable grate, 26b ......... Fixed grate, 27 ......... Oscillating rod, 28 ......... Ashes outlet, 29 ......... Inclined surface, 30 ......... Butt, 36 ... …… Smokeway.

Claims (5)

The fixed grate and the movable grate partially placed on the fixed grate are alternately arranged so that the movable grate can swing along the upper surface of the fixed grate, and the fixed grate and the In a stoker furnace that burns while extruding solid fuel on a movable grate,
A stoker furnace characterized by satisfying a relationship of H2> H1, where the height of the movable grate is H2 and the height of the solid fuel moving on the movable grate is H1.   The movable grate is partly placed on the side part partially placed on the fixed grate from the lower end of the side part toward the upper end with respect to the direction orthogonal to the upper surface of the fixed grate. The stoker furnace according to claim 1, wherein an inclined surface inclined at least 10 degrees is provided on the fixed grate side.   The movable grate is characterized in that a flange that protrudes on the fixed grate while being curved from the inclined surface is formed at a lower end of a side part partially placed on the fixed grate. The stoker furnace according to 2.   The height of the movable grate is H2, and the maximum particle diameter of the solid fuel is Dp100, and the relationship of H2 / Dp100> 1 is satisfied. Stalker furnace.   The movable grate according to any one of claims 1 to 4, wherein the movable grate is formed in a direction orthogonal to the moving direction of the solid fuel, and one or more places are formed between the fixed grate. Stoker furnace.

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