JP2018112391A - Combustor for solid fuel and boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustor and boiler, capable of preventing clinker from adhering to a refractory wall (wall surface) in a combustion furnace, upon combusting bamboo chips in the combustion furnace.SOLUTION: A combustor includes: a combustion furnace 5 at a bottom part 5b of which a fuel supply port 11 is formed, and at an upper part 5c of which a combustion gas discharge port 12 is formed; a fuel supply unit 6 configured to supply bamboo chips from the fuel supply port 11 of the combustion furnace 5 into the furnace; and air supply units 7, 39 configured to supply air so as to generate swirl flow at the lower part of the combustion furnace 5. At a position in a vertical direction of the combustion furnace 5, a constricted part 9 is formed. Provided are auxiliary air supply units 7, 40 configured to supply air from an inner peripheral surface of the constricted part 9 so as to cause air swirl flow passing through the constricted part 9.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solid fuel combustion apparatus for burning solid fuel such as bamboo, and a boiler apparatus equipped with the combustion apparatus.

  Bamboo is considered a promising fuel in the future because it is abundant in Japan and generates a large amount of heat during combustion. However, since bamboo contains a lot of silica components, when bamboo chips and the like are burned in a furnace, a large amount of clinker (molten ash) is generated, making it difficult to burn continuously.

  For example, when bamboo chips are burned on a grate in a furnace, the clinker clogs the grate and shuts off the supply of combustion air. Further, the clinker is fused to the refractory wall in the furnace, so that the refractory wall is deteriorated and it is difficult to continuously use the combustion furnace. When the clinker fused to the fire wall such as brick is to be removed, the fire wall may be peeled off from the furnace together with the clinker.

  By the way, Patent Document 1 discloses a combustion apparatus in which granular solid fuel is fed into a combustion furnace by a screw and burned. This combustion apparatus employs a method of burning solid fuel by supplying combustion air from the wall surface of the combustion pot without using a grate. Therefore, according to this combustion apparatus, the problem of clogging of the grate does not occur.

JP 2008-261527 A

  However, even in the combustion apparatus of Patent Document 1, a problem that a large amount of clinker adheres to the refractory wall of the combustion furnace (the pot inner peripheral surface 34, the inner peripheral surface 11 of the outer cylindrical portion 10 and the like of the same literature) occurs.

  The present invention was devised in view of the above problems, and when burning solid fuel such as bamboo in a combustion furnace, a combustion apparatus and a boiler apparatus in which clinker hardly adheres to a refractory wall (wall surface) in the combustion furnace. The purpose is to provide.

  In order to solve the above problems, a solid fuel combustion apparatus according to the present invention includes a combustion furnace having a fuel supply port formed at the bottom and a combustion gas discharge port formed at the top, and the fuel supply port of the combustion furnace. A fuel supply unit for supplying solid fuel into the furnace, and an air supply unit for supplying air so as to generate a swirling flow in the lower part of the combustion furnace, and at a position in the vertical direction in the combustion furnace. A constricted portion is formed.

  Preferably, in the solid fuel combustion apparatus, an auxiliary air supply unit that supplies air from an inner peripheral surface of the constricted portion is provided so as to promote a swirling flow of the air passing through the constricted portion.

  Preferably, in the solid fuel combustion apparatus, a temperature detection unit that detects a temperature in the vicinity of the wall surface below the constriction in the combustion furnace, and the furnace temperature detected by the temperature detection unit has a predetermined temperature. An in-furnace temperature control unit that controls a feeding speed of the solid fuel into the furnace by the fuel feeding unit so as not to exceed, and the predetermined temperature is in the range of 800 ° C. to 850 ° C. Let it be temperature.

  For example, the fuel supply unit includes a solid fuel supply cylinder having a tip connected to the fuel supply port of the combustion furnace, a screw disposed in the solid fuel supply cylinder, and the screw is driven to rotate. The screw is provided with a predetermined gap between the screw and the solid fuel supply cylinder, and the tip side is cantilevered so as to be swingable. it can.

  Further, the boiler device of the present invention is a solid fuel combustion device, a heat exchange device that introduces combustion gas discharged from a combustion gas discharge port of the combustion furnace, and exchanges heat between the combustion gas and liquid, Is provided.

  According to the present invention, when a solid fuel such as bamboo is burned in a combustion furnace, the clinker is hardly fused to a refractory wall (furnace bottom, wall surface) or the like in the combustion furnace.

It is a figure which shows the combustion apparatus and boiler apparatus which concern on embodiment of this invention. It is a figure for demonstrating the flame (fire column) which arises in a combustion apparatus. It is a cross-sectional view in the constriction part of a combustion furnace. It is a transverse cross section in the lower part of a combustion furnace.

  Hereinafter, a boiler apparatus provided with a solid fuel combustion apparatus according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the case where the solid fuel is bamboo chips will be described as an example.

  As shown in FIG. 1, a boiler device 1 according to an embodiment of the present invention mainly includes a combustion device 2 and a heat exchanger 3.

  The combustion apparatus 2 includes a combustion furnace 5, a fuel supply unit 6, an air supply circuit 7, a control unit 8, and the like.

  The combustion furnace 5 includes a substantially cylindrical trunk portion 5a having a constricted portion 9 in the middle in the vertical direction, a flat bottom portion 5b in which a fuel supply port 11 is formed, and an upper portion 5c in which a combustion gas discharge port 12 is formed. And is mainly composed. Inside the combustion furnace 5, solid fuel such as bamboo chips 13 can be burned continuously. The combustion furnace 5 is also provided with an opening 47 for supplying fuel from the outside, a door 48 for opening and closing the opening 47, a burner 50 for automatic ignition, and the like.

  The body 5a of the combustion furnace 5 is formed by coating the inner surface of a metal outer shell with a refractory heat insulating material (for example, brick), and the bottom 5b is formed of casters.

  As shown in FIG. 1, the constricted part 9 formed in the body part 5a of the combustion furnace 5 is formed at an intermediate position in the vertical direction of the body part 5a of the combustion furnace 5, and the inner diameter of the constricted part 9 is It is about 1/3 of the inner diameter of the 5d general portion (portion other than the constricted portion). The ratio of the inner diameter of the constricted portion 9 to the inner diameter of the general portion is not limited to the above, and it is desirable that the inner diameter of the constricted portion 9 is ½ or less of the inner diameter of the general portion.

  A spiral heat exchange tube 14 is disposed above the constricted portion 9 in the combustion furnace 5. Air is supplied into the heat exchange pipe 14, and the air is heated in the furnace, and then dried in the vicinity of the combustion furnace 5 in the second solid fuel supply cylinder 17 to be described later in order to dry the bamboo chips. Supplied.

  A water jacket 18 is provided on the outer peripheral portion of the combustion furnace 5 at a position higher than the constricted portion 9. Normal temperature water introduced from a water storage tank 19 installed at a position higher than the water jacket 18 is heated by the water jacket 18 and supplied to the heat exchanger 3 described later.

  The fuel feeding unit 6 feeds bamboo chips from the fuel supply port 11 of the combustion furnace 5 into the combustion furnace 5. 1 includes first and second solid fuel supply cylinders 16 and 17, first and second screws 21 and 22 provided in the solid fuel supply cylinders 16 and 17, respectively. The first and second driving devices 23 and 24 for rotating these screws 21 and 22 are configured. The first solid fuel supply cylinder 16 communicates with the bottom of a fuel storage hopper (not shown), and is provided so that the bamboo chips 13 flow from the fuel storage hopper. When the first and second driving devices 23 and 24 are driven, the first and second screws 21 and 22 rotate, and the bamboo chip 13 in the first solid fuel supply cylinder 16 flows in the axial direction. Then, it is supplied to the second solid fuel supply cylinder 17 side through the communication cylinder 26. Further, the bamboo chip 13 supplied to the second solid fuel supply cylinder 17 moves to the combustion furnace 5 side and is supplied into the combustion furnace 5 from the fuel supply port 11 formed in the bottom 5b of the combustion furnace.

  The second solid fuel supply cylinder 17 is disposed in the horizontal direction and is bent upward in the vicinity of the fuel supply port 11 of the combustion furnace 5. As shown in FIG. 1, the outer diameter portion of the bent portion 17a is formed in a circular arc shape in cross section. Although it is desirable to use bamboo chips that have been dried to some extent, bamboo chips containing a relatively large amount of moisture may be used as fuel. Such bamboo chips may become clogged at the bent portion when flowing in the bent tube. However, according to the second solid fuel supply cylinder 17, since the outer diameter portion of the bent portion 17a is formed in an arc shape in cross section, it is possible to prevent the bamboo chip from being clogged in the bent portion 17a. it can.

  The second screw 22 is installed between the second solid fuel supply cylinder 17 via a predetermined gap (a gap of a size that can sufficiently swing the tip side) so that the tip side can swing. The end side is cantilevered rotatably. For this reason, the tip side of the second screw 22 is flexibly swung according to the flow state of the bamboo chip 13, and the bamboo chip is prevented from being clogged by the bent portion 17 a of the second solid fuel supply cylinder 17.

  The air supply circuit 7 includes a blower 27, a reference pipe 28, a heat exchange pipe 29, a swirling air supply pipe 30, a dry air supply pipe 31, valves 32 to 34, and the like.

  One end of a reference pipe 28 and a swirling air supply pipe 30 are connected to the discharge side of the blower 27. The other end of the invitation pipe 28 is connected to the chimney 36, and supplies the induction air to the chimney 36. The swirling air supply pipe 30 is branched into two in the middle, one is connected to an air box 37 formed on the outer periphery of the combustion furnace 5, and the other is formed in the constricted portion 9 of the combustion furnace 5. The air box 38 is connected. As shown in FIGS. 3 and 4, the air supplied to the air boxes 37 and 38 by the swirling air supply pipe 30 is supplied from the air blowing holes 39 and 40 provided on the wall of the combustion furnace 5. It comes to blow out inside. In addition, since the air blowing holes 39 and 40 are formed in a direction inclined from the center direction of the combustion furnace 5, a swirling flow is generated in the combustion furnace 5. Note that three air blowing holes 39 are provided in two upper and lower stages.

  The heat exchange pipe 29 is branched from the reference pipe 28 and connected to one end of the spiral heat exchange pipe 14. A dry air supply pipe 31 is connected between the other end of the heat exchange pipe 14 and the vicinity of the combustion furnace 5 of the second solid fuel supply cylinder 17. As a result, the air heated and dried in the heat exchange pipe 14 is supplied to the vicinity of the combustion furnace 5 in the second solid fuel supply cylinder 17, and the bamboo chip 13 in the place is dried. Thereby, the combustion efficiency of the bamboo chip | tip supplied in the combustion furnace 5 can be improved.

  The valves 32 to 34 are provided to open and close the flow paths in each pipe or adjust the flow rate.

  The control unit 8 feeds the bamboo chip 13 into the combustion furnace 5 by the fuel feeding unit 6 so that the temperature in the vicinity of the wall surface 5d below the constricted part 9 in the combustion furnace 5 does not exceed the set temperature. To control. Specifically, when the temperature at the temperature measurement position detected by the temperature sensor 42 rises to T1 ° C. (for example, any temperature in the range of 800 ° C. to 850 ° C.), the control unit 8 takes a bamboo chip for a predetermined time. Supply to the combustion furnace 5 (rotation drive of the first and second screws 21 and 22) is stopped or decelerated, and then the supply of bamboo chips to the combustion furnace 5 is resumed. Thereafter, the above operation is repeated. In the apparatus prototyped by the applicant, the temperature T1 ° C. is set to 820 ° C., and the supply stop time of the bamboo chip into the combustion furnace 5 is set to 15 minutes so that the temperature measurement temperature does not exceed 850 ° C. did. In addition, it is said that a clinker is hard to generate | occur | produce at 850 degrees C or less.

  When the control unit 8 performs the above control, the temperature rise in the combustion furnace 5 can be suppressed so as not to exceed the predetermined temperature, and the temperature in the vicinity of the wall surface in the combustion furnace 5 exceeds the predetermined temperature (for example, 850 ° C.). Thus, it is possible to make it difficult for the clinker to be generated in the vicinity of the inner wall surface of the furnace.

  The heat exchanger 3 introduces the combustion gas discharged from the combustion gas discharge port 12 of the combustion furnace 5 and heat-exchanges the combustion gas and the liquid (water). The heat exchanger 3 shown in FIG. 1 is provided with an upper introduction port 43, a lower introduction port 44, and a discharge port 45. Hot water led out from the water jacket 18 is introduced into the upper introduction port 43. Room temperature water is introduced into the lower introduction port 44 from a water storage tank 19 which is installed at a higher position than the heat exchanger 3 and automatically maintains the water level. The hot water and normal temperature water introduced into the heat exchanger 3 are heated by the combustion gas discharged from the combustion furnace 5 and led out from the discharge port 45. The derived hot water is used for various facilities as a heat energy source. In addition, although the water storage tank 19 is installed in the high position and the said water circulation is performed by the water head difference, you may install the pump and perform the water circulation forcibly.

  When using the boiler apparatus 1 demonstrated above, first, the screws 21 and 22 are rotationally driven, the bamboo chip | tip 13 is supplied in the combustion furnace 5, and bamboo is supplied from the furnace bottom (the upper surface of the bottom part 5b of the combustion furnace 5). As long as the chip 13 is lifted, the burner 50 automatically ignites for a predetermined time (eg, 3 minutes). After confirming ignition by a temperature sensor 42 (this temperature sensor 42 includes a display unit that transmits temperature information to the control unit 8 and displays the temperature in the furnace), the combustion of the burner 50 is stopped. The burner 50 only blows air. At this time, the supply amount of the bamboo chips 13 is suppressed so that the bamboo chips do not reach the wall surface 5d of the combustion furnace 5. The bamboo chips are supplied into the combustion furnace 5 by the screws 21 and 22 as described above. However, the bamboo chips can be supplied from the opening 47 by opening the door 48.

  Subsequently, a certain amount of bamboo chips per hour is supplied into the combustion furnace 5 and the blower 27 is driven to open the valves 32 to 34 as appropriate.

  In this way, the bamboo chip 13 continuously supplied into the combustion furnace 5 starts burning, but in the combustion furnace 5, as shown in FIGS. 3 and 4, the center of the furnace is formed from the air blowing holes 39 and 40. Since combustion air is ejected into the furnace in a direction inclined with respect to the direction, a swirling flow (upward swirling flow) is generated in the combustion furnace 5. And since the constriction part 9 is provided, as shown in FIG. 2, from the bamboo chip | tip 13 in a furnace to the constriction part 9, the fire pillar 49 forms in the position away from the wall surface 5d in the combustion furnace 5. As shown in FIG. After passing through the constricted part 9, the fire pillar 49 diffuses in the combustion furnace 5. As with the fire column 49, the ash also flows at a position away from the wall surface 5d. For this reason, molten ash (clinker) hardly adheres to the wall surface 5d.

  As is apparent from the above description, the solid fuel combustion apparatus 2 according to the embodiment of the present invention can prevent the clinker from adhering to the wall surface 5 d in the combustion furnace 5.

  Although the flame diffuses to the vicinity of the wall surface 5d above the constricted portion 9, since the ash content in the combustion air is small at this position, the clinker is hardly fused to the wall surface 5d.

  The present invention is applicable to, for example, a bamboo chip combustion apparatus and a boiler apparatus equipped with this combustion apparatus.

1 Boiler device 2 Combustion device 3 Heat exchanger (Heat exchange device)
DESCRIPTION OF SYMBOLS 5 Combustion furnace 5b Bottom part 5c Upper part 5d Wall surface 6 Fuel supply part 7 Air supply circuit (Air supply part, auxiliary air supply part)
8 Control part (In-furnace temperature control part)
9 Constriction part 11 Fuel supply port 12 Combustion gas discharge port 13 Bamboo chip (solid fuel)
17 2nd solid fuel supply cylinder 22 2nd screw 24 2nd drive device 39 Air blowing hole (air supply part)
40 Air outlet (auxiliary air supply part)
42 Temperature sensor (temperature detector)

Claims (5)

A combustion furnace having a fuel supply port formed at the bottom and a combustion gas discharge port formed at the top;
A fuel supply section for supplying solid fuel from the fuel supply port of the combustion furnace into the furnace;
An air supply unit for supplying air so as to generate a swirling flow in a lower part in the combustion furnace;
In a solid fuel combustion apparatus comprising:
A solid fuel combustion apparatus, characterized in that a constriction is formed at an intermediate position in the vertical direction in the combustion furnace. The solid fuel combustion apparatus according to claim 1,
A combustion apparatus for solid fuel, characterized in that an auxiliary air supply unit for supplying air from an inner peripheral surface of the constricted portion is provided so as to promote a swirling flow of air passing through the constricted portion. The solid fuel combustion apparatus according to claim 1 or 2,
A temperature detection unit for detecting the temperature in the vicinity of the wall surface below the constriction in the combustion furnace;
An in-furnace temperature control unit for controlling the feed rate of the solid fuel into the furnace by the fuel feed unit so that the in-furnace temperature detected by the temperature detection unit does not exceed a predetermined temperature;
Further comprising
The solid fuel combustion apparatus according to claim 1, wherein the predetermined temperature is any temperature within a range of 800C to 850C. The solid fuel combustion apparatus according to any one of claims 1 to 3,
The fuel supply unit is
A solid fuel supply cylinder having a tip connected to the fuel supply port of the combustion furnace;
A screw disposed in the solid fuel supply cylinder;
A drive for rotating the screw;
Having
The screw is provided between the solid fuel supply cylinder via a predetermined gap, and the tip side is cantilevered so as to be swingable.
A solid fuel combustion apparatus. A solid fuel combustion device according to any one of claims 1 to 4,
A heat exchange device that introduces combustion gas discharged from the combustion gas discharge port of the combustion furnace and heat-exchanges the combustion gas and the liquid;
A boiler device comprising:

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