Combustion Furnace and Combustion Furnace System

Abstract

To provide a combustion furnace having a simple structure and capable of efficiently combusting a waste solid fuel, and a combustion furnace system.SOLUTION: A combustion furnace 1 comprises a combustion chamber 11 that combusts fuel R to cause primary combustion, and a heat riser 13 that causes secondary combustion, where the combustion chamber and the heat riser are arranged in a generally L-shape and communicate with each other. The combustion chamber is provided with a heating pipe 11c that is arranged in the combustion chamber and heats the air flowing therethrough to a temperature above an ignition point of the fuel. The heating pipe has a hot air blowout port 11d through which the air heated in the combustion chamber blows out. The air blown out from the hot air blowout port has a wind pressure that blows the fuel introduced into the combustion chamber from a front side to the heat riser side arranged on the back side.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention mainly relates to a combustion furnace and a combustion furnace system that can be suitably used with waste solid fuels such as RPF (abbreviation for Refuse derived paper and plastics densified Fuel; hereinafter referred to as RPF) using waste plastics and the like as raw materials as fuel.

Background Art

[0002] Conventionally, as small combustion furnaces, wood pellet stoves and firewood boilers that can burn a large amount of firewood for a long time are known. However, as a heating device used in house cultivation and the like, there are problems in that the fuel cost is high and the amount of heat is insufficient. In addition, in the combustion furnace of a firewood-fired hot water boiler, combustion is not constant due to the moisture content of the firewood itself as fuel and the difference in tree species, so it is difficult to achieve stable combustion. Furthermore, most of the commonly used combustion furnaces have used fossil fuels such as petroleum. However, due to the problem of carbon dioxide reduction and cost reduction, a combustion furnace that can use an inexpensive fuel instead of petroleum is required.

[0003] Therefore, waste solid fuels have attracted attention as inexpensive and high-calorie fuels. As waste solid fuels, those obtained by pulverizing materials from which chlorine-based plastics have been excluded as much as possible from plastic waste and mixing them with papers, woody waste, etc. into pellets or dumplings, such as RPF and RDF (Refuse Derived Fuel), are known. In recent years, in order to realize the transition to a sustainable recycling society, from the viewpoint of the utilization of waste plastics, the movement to utilize waste solid fuels such as RPF as fuel has become active, and the development of a combustion furnace that enables stable combustion for a long time and has a small and simple structure is further demanded.

[0004] However, when burning solid waste fuels such as RPF in a general combustion furnace, since the combustion temperature is as low as around 500 degrees, black smoke and strange odors are generated. In addition, since unburned and melted plastics adhere to the inside of the combustion furnace, it is realistically difficult to use RPF or the like as fuel in a combustion furnace for burning ordinary firewood. Furthermore, in the low-temperature combustion as described above, the generation of dioxins is also a concern, so it is necessary to burn at a high temperature of 800 degrees or more. However, when burning at a high temperature in a conventional combustion furnace, the ash accumulated inside the combustion furnace melts and solidifies due to the high heat, reducing the volume inside the combustion chamber, deteriorating the flow of combustion air, and making it impossible to achieve stable combustion for a long time.

[0005] Patent Document 1 below discloses a hot air generator that adopts a rotary kiln method and uses solid waste fuel as fuel. Here, it is provided with an air supply means for supplying combustion air for reburning to a storage hopper that stores the combustion ash and solid unburned components of the solid fuel discharged from the kiln body, and it is described that the solid unburned components are burned and decomposed into ash by the combustion air for reburning.

[0006] Patent Document 2 below discloses an RPF combustion furnace. Here, it is provided with a plurality of primary combustion air outlets at the lower front part of the combustion furnace and a secondary combustion air blowing pipe having a plurality of blow holes near the upper rear part of the combustion furnace. It is disclosed that primary fuel air is blown onto the RPF for combustion, and the combustion flame and unburned fine powder are blown into the back of the combustion chamber, and hot air of secondary combustion air is injected from above onto the unburned fine powder for complete combustion.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] Since the one disclosed in the above Patent Document 1 is of the rotary kiln type, a rotary mechanism is essential, making it difficult to miniaturize the device and difficult to simplify the structure. Further, although the one disclosed in the above Patent Document 2 has a structure that enables miniaturization, high-pressure air is sent from above the combustion chamber to blow the solid fuel to the back of the combustion chamber, and the high-temperature secondary combustion air is blown to burn the solid fuel. Therefore, if the distance between the back of the combustion chamber and the ash storage part is short, the unburned fuel may fly to the ash storage part at the back of the combustion chamber without being burned, and unburned fuel may remain due to oxygen deficiency. This is considered to occur because the raw material of RPF is waste and the inflow rate of combustion air corresponding to the change in combustion rate due to the difference in combustion calorific value cannot be adjusted. Also, if the temperature of the combustion air sent into the combustion chamber does not reach the ignition temperature of the solid fuel, it will ignite after reaching the back of the combustion chamber. Therefore, until the solid fuel burns out, it accumulates in the ash storage part at the back of the combustion chamber, and ash accumulates on top of it. Thus, unburned fuel may also be generated due to oxygen deficiency.

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a combustion furnace and a combustion furnace system that have a simple structure and can efficiently burn waste solid fuel.

Means for Solving the Problems

[0010] In order to achieve the above object, a combustion furnace according to the present invention includes a combustion chamber that burns fuel to cause primary combustion, and a heat riser that causes secondary combustion, and the combustion furnace is arranged such that the combustion chamber and the heat riser communicate with each other in a substantially L-shape. In the combustion chamber, a heating pipe is provided in which the air flowing through the combustion chamber is heated to a temperature exceeding the ignition point of the fuel. The heating pipe has a hot air outlet from which the air heated in the combustion chamber blows out, and the air blowing out from the hot air outlet has a wind pressure that blows the fuel input into the combustion chamber from the front side to the heat riser side arranged from the front side to the back side.

[0011] In order to achieve the above object, the fuel furnace system according to the present invention has a rocket stove structure including a combustion chamber that burns fuel to cause primary combustion and a heat riser that causes secondary combustion. In the combustion chamber, a heating pipe is provided through which the air flowing through the combustion chamber is heated to a temperature exceeding the ignition point of the fuel. The heating pipe has a hot air outlet from which the air heated in the combustion chamber blows out, and the air blowing out from the hot air outlet has a wind pressure that blows the fuel introduced into the combustion chamber from the front side to the heat riser side arranged from the front side to the back side, and the gas, fly ash, etc. generated in the heat riser Upward It is characterized by including a dust collector having a cyclone that uses an updraft to collect dust and forcibly exhausts air.

Effect of the Invention

[0012] Since the combustion furnace and the combustion furnace system of the present invention have the above-described configuration, they can efficiently burn waste solid fuel while having a simple structure.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the combustion furnace 1 and the combustion furnace systems 100 and 100A according to this embodiment will be described with reference to FIGS. 1 to 4. The combustion furnace 1 shown here is a so-called rocket stove type combustion furnace. The combustion furnace 1 includes a combustion chamber 11 that burns fuel R to cause primary combustion, a heat riser 13 that causes secondary combustion, and the combustion chamber 11 and the heat riser 13 are arranged to communicate with each other in a substantially L shape. The combustion chamber 11 constitutes a burner tunnel provided in a substantially horizontal direction below the heat riser 13, and the heat riser 13 is a heat rising furnace provided in a substantially vertical direction with respect to the combustion chamber 11. Thereby, when the flame and combustion gas generated in the combustion chamber 11 pass through the heat riser 13, a strong upward airflow is generated and secondary combustion can occur inside the heat riser. In the illustrated example, an example where the combustion chamber 11 and the heat riser 13 are arranged to communicate with each other in a substantially L shape is shown, but it is not limited thereto, and it may be a substantially J-shaped combustion furnace having a burner opening for the combustion chamber provided at an upper position. Also, in the illustrated example, the cross-sectional area configuration of each of the combustion chamber 11, the heat riser 13, and the exhaust pipe 4a is such that the combustion chamber 11 is configured to be large, but it is not limited thereto, and they may all have substantially the same cross-sectional area, or for example, the cross-sectional area of the heat riser 13 may be configured to be larger than that of the combustion chamber 11, and the cross-sectional area of the exhaust pipe 4a may be configured to be larger than that of the heat riser 13 to increase the combustion efficiency.

[0015] The fuel R used here is preferably RPF, which has been difficult to be a fuel for stable combustion heretofore. According to the combustion furnace 1 according to the present embodiment, since RPF can be efficiently combusted at a high temperature of 800 degrees or more, there is no risk that unburned and melted plastic adheres in the combustion chamber 11, and there is also no risk of generation of black smoke or strange odor generated during low-temperature combustion. As RPF, those commercially available as inexpensive and high-calorie fuels can be used. Those with a diameter of 8 mm and a diameter of 40 mm are generally in circulation, but either can be used. Further, the fuel R may be other than RPF, and various wood materials described later may be mixed with RPF and used, or may be used as the fuel R without mixing. Examples of the wood materials include twigs, fallen leaves, firewood, logs, square timbers, and waste building materials. Further, waste wood chips for shiitake log cultivation, bamboo chips, crushed PET bottle fluff, woody sawdust briquettes, etc. used in the combustion test described later may be mixed with RPF, or may be used as the fuel R without mixing.

[0016] As shown in FIGS. 1 and 2, the combustion furnace 1 includes a fuel hopper 2 that sends out and stores the fuel R in the combustion chamber 11, a blower 3 that supplies air to the heating pipe 11c, a dust collector 4 that collects fly ash, dust, etc. contained in the secondary combustion air that has passed through the heat riser 13, an ash storage section 5 that stores ash at the lower part of the cyclone 40 of the dust collector 4, and an exhaust blower 6 that exhausts the air purified by the cyclone 40 in addition to high-temperature combustion, thereby constituting the combustion furnace system 100. The structure of the cyclone 40 is not particularly limited, and for example, a centrifugal force method or a ventilation method may be used.

[0017] The fuel hopper 2 has an inlet opening at the upper part and is formed in a funnel shape that gradually narrows downward, configured to store a large amount of fuel R. A screw 21 for sending the fuel R to the combustion furnace 1 is provided on the lower side thereof. The fuel hopper 2 has an input control unit 20 capable of automatically controlling the input amount of the fuel R. The input control unit 30 includes a CPU 20a for performing various controls and a screw activation unit 20b for rotating and activating the screw 21. The fuel hopper 2 and the combustion furnace 1 are connected by a fuel supply pipe 2a through which the fuel R passes, and the fuel R is introduced from the fuel inlet 11a through the fuel supply pipe 2a. Note that the configuration for storing the fuel R is not limited to the illustrated example, and the means for transporting the fuel R is not limited to the screw 21 type conveyor, and may be a belt type conveyor.

[0018] The combustion furnace 1 is provided with a temperature control unit 10. The temperature control unit 10 includes a CPU 10a for performing various controls, an operation unit 10b for operating the temperature setting, a display unit 10c for displaying the temperature inside the combustion chamber 11, etc., and a temperature detection unit 10d for detecting the temperature inside the combustion chamber 11, etc. This temperature control unit 10 is electrically connected to the input control unit 20. Therefore, when it is set by the operation unit 10b of the temperature control unit 10 to set the temperature inside the combustion chamber 11 to 800 °C, for example, the input amount of the fuel R is controlled according to this temperature setting. As a result, automatic input of the fuel R becomes possible, and continuous combustion operation becomes possible.

[0019] The combustion chamber 11 is provided with a fuel inlet 11a, an opening and closing door 11b with a glass window, and a heating pipe 11c. The fuel inlet 11a is provided to open above the combustion chamber 11, and the fuel R carried through the fuel supply pipe 2a is configured to fall in a scattered manner from above to a position surrounded by the heating pipe 11c as shown in Fig. 3(a). The opening and closing door 11b is attached to be openable and closable so as to close the opening 11ba formed on the front side surface of the combustion chamber 11. A glass window is provided on the opening and closing door 11b, and the inside of the combustion chamber 11 can be seen through this glass window even when the opening and closing door 11b is closed. The heating pipe 11c is made of a metal material or the like and is provided inside the combustion chamber 11 as shown in Figs. 3(a) and 3(b). The heating pipe 11c is connected to a blower pipe 3a that carries the air supplied from the blower 3, forms a substantially inverted L shape in side view and a substantially rectangular shape in plan view, and has a space for injecting the fuel R in the center surrounded by the heating pipe 11c. In the illustrated example, the heating pipe 11c shows a square hollow pipe, but it is not limited to this and may be round.

[0020] The heating pipe 11c includes straight portions 11ca, 11ce arranged along the bottom 11e of the combustion chamber 11 from the fuel inlet 11a side toward the back side of the combustion chamber 11, upright portions 11cb, 11cd formed in a substantially L shape in side view toward the heater 13 side, a bridging portion 11cc provided between the upright portions 11cb, 11cd, and a blowing portion 11cf arranged near the opening and closing door 11b facing the bridging portion 11cc. As shown in Fig. 3(a), a plurality of hot air outlets 11d are provided in the blowing portion 11cf. The number of the hot air outlets 11d is not limited to 4 in the illustrated example and is set according to the size of the combustion chamber 11 and the like.

[0021] The heating pipe 11c may be formed by bending a single hollow pipe, etc. The end 11cg of the blowing part 11cf abuts against the outer wall surface of the straight part 11ca on the blower pipe 3a side. Therefore, the air passing through the heating pipe 11c is first supplied from the blower 3 through the blower pipe 3a as shown by the arrow in Fig. 3(a), passes through the straight part 11ca, and after passing through the standing part 11cb, the bridging part 11cc, and the standing part 11cd, it passes through the straight part 11ce and reaches the blowing part 11cf. That is, the air flow is one-way, and since there is no place for the air that has reached the blowing part 11cf to go, it blows out from the hot air outlet 11d. The air passing through the heating pipe 11c before reaching this hot air outlet 11d is heated to a high temperature by the combustion heat inside the combustion chamber 11, so when it blows out from the hot air outlet 11d, it is hot air. By arranging the heating pipe 11c in the combustion chamber 11 in the shape shown in Fig. 3(a) in this way, the air flowing through the heating pipe 11c can be heated to the same temperature as inside the combustion chamber 11. And at this time, the air blowing out from the hot air outlet 11d has a wind pressure that blows the fuel R input into the combustion chamber 11 from the front side to the heat radiator 13 side arranged from the front side to the back side inside the combustion chamber 11. The adjustment of the wind pressure can be adjusted by the blower 3.

[0022] The shape and structure of the heating pipe 11c are not limited to the illustrated example. For example, it may be made to meander or complicated so as to be sufficiently heated inside the combustion chamber 11. However, the shape shown in Fig. 3(a), etc., can sufficiently heat the air passing through the heating pipe 11c while maintaining the wind pressure and having a simple structure without hindering the input of the fuel R.

[0023] The rising position of the rising part 11cd of the heating pipe 11c is not limited to the position directly below the front of the heater 13 as shown in the illustrated example. For example, since the flow of the flame may change according to the fuel R, it may be at any position from the inner part of the heater 13 to the front part on the drawing. The key point is that the air blown out from the hot air outlet 11d is made into high-temperature hot air and has the wind pressure to blow the fuel R input into the combustion chamber 11 from the front side to the heater 13 side arranged from the front side to the back side of the combustion chamber 11. With the above configuration, the fuel R input into the combustion chamber 11 is blown from the front side to the heater 13 side and then to the back side by the air blown out from the hot air outlet 11d, so that the fuel R can be efficiently burned while being blown to the back side of the combustion chamber 11. Moreover, since the air blown out from the hot air outlet 11d is the hot air heated in the combustion chamber 11, the fuel R can be rapidly burned to guide the combustion flame and combustion ash to the heater 13 side, and a combustion close to complete combustion can be realized at a higher temperature and more efficiently in the primary combustion stage. The temperature of the air blown out from the heating pipe 11c needs to be heated above the ignition temperature of the fuel R to promote primary combustion. For example, the ignition point (ignition temperature) of RPF is 200 to 230 degrees, and that of wood materials is 400 to 500 degrees. However, since the fuel furnace 1 can control the temperature around 800 degrees, the temperature of the air passing through the heating pipe 11c can be heated to a temperature sufficiently exceeding the ignition point (ignition temperature).

[0024] The combustion furnace 1 further includes a heater 13 and a heat dissipation cylinder 12. The heater 13 has a substantially cylindrical chimney structure, and the periphery of the heater 13 is covered with a heat dissipation cylinder 12 made of a heat insulating material. Thereby, the heater 13 can be maintained at a high temperature, and an upward air flow is generated by the chimney effect of the heater 13. In this way, the combustion flame and combustion ash generated in the above-mentioned combustion chamber 11 can be promoted for secondary combustion of the fuel R by the upward air flow due to the draft effect of the heater 13. Also, with this upward air flow, the fly ash can be quickly transported to the cyclone 40 without storing it in the combustion chamber 11, so that the ash accumulation inside the combustion chamber 11 can be significantly suppressed (see Fig. 5(c)), and stable combustion for a long time can be realized.

[0025] The heater 13 and the dust collector 4 are connected via an exhaust pipe 4a. The dust collector 4 has a cyclone 40 that collects dust such as gas and fly ash generated in the heater 13 by using the upward airflow and forcibly exhausts it. Below the dust collector 4, there is an ash storage section 5 for storing the collected ash, dust, etc. On the other hand, the dust collector 4 is also connected to an exhaust blower 6. The ash storage section 5 is provided at a position separated from the combustion chamber 11 and the heater 13. Dust such as ash is induced into the ash storage section 5 by the cyclone 40, and the air purified by the cyclone 40 is attracted to the exhaust blower 6 and exhausted to the outside by the exhaust blower 6.

[0026] According to the combustion furnace system 100 with the above configuration, the fuel R fed at a constant speed from the fuel hopper 2 through the screw 21 is dropped into the combustion chamber 11, stably burned, and the ash of the combustion residue is also smoothly and quickly discharged from the combustion chamber 11. Therefore, the generation of ash melting (clinker) can be suppressed. Also, since the fuel R is burned at a level close to complete combustion, stable combustion can be achieved for a long time without emitting bad odors or black smoke. Due to the recent global fuel price hike, where a heat source is required, there is a significant increase in fuel cost and it is a cause for concern. However, by using RPF with a current unit price of about 10 yen as the fuel R, a significant reduction in fuel consumption can be achieved compared to kerosene fuel. Also, the development of the combustion furnace 1 and the combustion furnace system 100 that realize long-term stable combustion of RPF, which was not achievable with conventional small combustion furnaces, can greatly contribute to society and has effective effects in the effective utilization of waste and the reduction of marine plastic pollution. Also, since a predetermined amount of fuel R can be automatically fed into the combustion furnace 1 and maintained at a desired temperature, it can be applied to, for example, heating systems for houses and facilities, and heating systems for greenhouse cultivation of agricultural plants.

[0027] In addition to the configuration of the combustion furnace system 100 described above, if a heat exchanger 8 and a water storage tank 9 are provided as shown in FIG. 4 to form a combustion furnace system 100A, a hot water boiler can be configured. At this time, if the cyclone 40 and the heat exchanger 8 are attached to the same water storage tank 9 as shown in FIG. 4, the size of the hot water boiler can be reduced, and the heat radiation from the cyclone 40 can be efficiently taken in, so that the heat exchange capacity can also be improved. Further, in the combustion furnace system 100A of the present embodiment, since only the hot air purified by removing ash and dust discharged from the combustion chamber 11 by the cyclone 40 can be sent to the heat exchanger 8, dirt is less likely to adhere to the inside of the heat exchanger 8, and maintenance work can be reduced.

[0028] Next, the combustion furnace 1 and the combustion furnace system 100 according to the present embodiment will be further described with reference to FIGS. 5 and 6, including combustion tests actually performed using various fuels.

[0029] The above Patent Document 2 was developed by the present inventor. The combustion furnace of Patent Document 2 automatically supplies a certain amount of fuel into the combustion chamber, sends combustion air to the supplied fuel, blows it to the back of the combustion chamber, and burns it by hot air injection from a secondary combustion air outlet pipe provided at the back of the combustion chamber, and adopts a structure in which combustion residues such as ash are sent into an ash storage section provided at the back of the combustion chamber. However, as a result of the combustion experiment using this combustion furnace, when burning by blowing the secondary combustion air that has been blown to the back of the combustion chamber and has become high temperature, since the distance between the back of the combustion chamber and the ash storage section is short, it flies to the ash storage section at the back of the combustion chamber without being burned, and there may be unburned due to oxygen deficiency. In addition, since the temperature of the combustion air sent to the fuel input into the combustion chamber does not reach the ignition temperature of the fuel, it accumulates in the ash storage section at the back of the combustion chamber until it ignites after reaching the back of the combustion chamber and the fuel burns out, and if ash accumulates on top of it, unburned may occur due to oxygen deficiency. Therefore, the present inventor has further developed and completed the combustion furnace 1 and the combustion furnace system 100 (100A) according to the present embodiment in order to improve the structure to solve Problem 1. Ignite immediately after fuel input, Problem 2. Perform complete combustion in the combustion chamber 11, and Problem 3. Quickly discharge combustion residues from the combustion chamber 11.

[0030] <Regarding Problem 1> First, after fuel R is introduced into the combustion chamber 11, in order to ignite it immediately, a heating pipe 11c is provided inside the combustion chamber 11, and air is sent in by the blower 3 through the air supply pipe 3a connected to this heating pipe 11c. The air sent in is heated by the combustion heat in the combustion chamber 11 while traveling through the straight part 11ca, upright part 11cb, bridging part 11cc, upright part 11cb, and straight part 11ca of the heating pipe 11c. When it reaches the hot air outlet 11d, the air temperature sufficiently exceeds about 230 degrees, the ignition point of the fuel. By blowing the heated air onto the dropped fuel R, we successfully ignited the fuel R immediately (see Fig. 5(b)).

[0031] <Regarding Problem 2> In order to sufficiently burn the fuel R in the combustion chamber 11 to a level where it can be said to be completely burned, the structure of the combustion furnace 1 is made into the structure of the combustion method of a rocket stove. Since the combustible gas remaining unburned in the combustion chamber 11 rises and burns in a state of being exposed to high temperature when passing through the inner cylinder of the heat riser 13 part of the rocket stove, there is almost no residue of the fuel R left unburned, and we successfully burned it sufficiently (see Fig. 5(c)). <Regarding Problem 3> As a method of immediately discharging the combustion residue from the combustion chamber 11, by blowing high-temperature air that sufficiently exceeds the ignition temperature of the fuel onto the surface of the dropped fuel R from the hot air outlet 11d, combustible gas is generated by the heat reaction from the outer surface of the fuel R, and the fuel R can be burned efficiently. At this time, the waste plastic contained in the fuel R does not melt and become liquid, and because the combustion speed is fast, the ash of the combustion residue does not melt and is quickly discharged outside the combustion chamber 11 by the upward airflow of the heat riser 13, the cyclone 40, and the negative pressure effect of the exhaust blower 6 in a powder state (see Fig. 5(c) and Fig. 6(a)).

[0032] The combustion furnace 1 and the combustion furnace system 100 according to this embodiment were subjected to combustion tests on various fuels for 12 hours or more continuously, and are listed below. <Combustion Test Using 8 - millimeter - diameter RPF> Combustion tests were conducted using RPF with a diameter of 8 mm. Since it is small and pellet-shaped, it is easy to automatically feed, and it can be ignited immediately after being dropped into the combustion chamber and burn stably. Figure 5(a) shows the display part when combustion tests were conducted using RPF with a diameter of 8 mm. The temperature in the combustion chamber reached 870.6 °C and could be kept around 860 °C. Figure 5(b) is a photo taken during the combustion in this combustion test. From this photo, no fuel can be confirmed in front of the combustion chamber, and it can be confirmed that it is being thrown to the back side and the combustion flame is rising on the back side of the combustion chamber. In this combustion test, 600 Kg of RPF filled in the fuel hopper was used (see Figure 6(b)). About 12 Kg was consumed per hour, the single input amount was around 50 g (about a handful), and continuous combustion for 50 hours was successful. The photo taken from above of the fuel hopper after 50 hours is Figure 6(c), and the photo taken of the ash stored in the ash storage part discharged in this combustion test is Figure 6(a). From the photo in Figure 6(a), it can be seen that unmolten plastics, etc. cannot be confirmed, and good-quality ash is being recovered. Also, Figure 5(c) is a photo taken of the state of the combustion chamber after this combustion test. From this photo, it can be seen that no adhesion of unburned and molten plastics can be confirmed from the front side to the back side of the combustion chamber.

[0033] <Combustion Test Using RPF with a Diameter of 40 mm> Combustion tests were conducted using RPF with a diameter of 40 mm. Even in the case of RPF with a diameter of 40 mm, it could be ignited immediately after being dropped into the combustion chamber and burn stably, similar to the RPF with a diameter of 8 mm. In the case of RPF with a diameter of 40 mm, some contained glass wool which is a non-combustible material, and since this glass wool melts and remains in the combustion chamber, it was found that it is desirable to use those without such non-combustible materials mixed in.

[0034] <Combustion Test Using Waste Wood Chips for Shiitake Log Cultivation> Combustion tests were conducted using waste wood chips for shiitake log cultivation. Even with the waste wood chips for shiitake log cultivation, they could be ignited immediately after being dropped into the combustion chamber and burned stably. Although the calorific value of the waste wood chips for shiitake log cultivation is lower compared to RPF, more fuel is required to obtain the same amount of heat as in the case of RPF. Also, since the specific gravity is light, it is difficult to ride on the screw, so it was found that it is advisable to attach a vibrator to the fuel hopper and intermittently vibrate it while feeding.

[0035] <Combustion Test Using Bamboo Chips> Combustion tests were conducted using bamboo chips. Even with the bamboo chips, they could be ignited immediately after being dropped into the combustion chamber and burned stably. Although the calorific value of the bamboo chips is higher than that of the waste wood chips for shiitake log cultivation, more fuel is required to obtain the same amount of heat as in the case of RPF.

[0036] <Combustion Test Using Ground PET Bottle Fluff> Combustion tests were conducted using ground PET bottle fluff. Even with the ground PET bottle fluff, it could be ignited immediately after being dropped into the combustion chamber and burned stably. In the combustion test of the ground PET bottle fluff, assuming that when used cooking oil is collected in PET bottles and the PET bottles are difficult to recycle due to the oil adhering to them, they are ground into fuel, a combustion test was conducted by sprinkling about 10% of used cooking oil on the ground PET bottle fluff. In this case, the combustion was almost the same as that of RPF, and the amount of ash was very small.

[0037] <Combustion Test Using Wood Sawdust Briquettes> Combustion tests were conducted using wood sawdust briquettes. Even with the wood sawdust briquettes, they could be ignited immediately after being dropped into the combustion chamber and burned stably. Similar to the bamboo chips, the calorific value of the wood sawdust briquettes is higher than that of the waste wood chips for shiitake log cultivation, but more fuel is required to obtain the same amount of heat as in the case of RPF.

[0038] As described above, the configurations and aspects of the combustion furnace 1 and the combustion furnace system 100 (100A) according to the present embodiment are not limited to the above embodiment.

Explanation of Signs

[0039] 1 Combustion furnace 100, 100A Combustion furnace system 10 Temperature control unit 11 Combustion chamber 11a Fuel inlet 11b Opening / closing door 11c Heating pipe 11d Hot air outlet 12 Heat dissipation cylinder 13 Heater 2 Fuel hopper 3 Blower 4 Dust collector 5 Ash storage section 6 Exhaust blower 9 Water storage tank 8 Heat exchanger R Fuel

Claims

1. A combustion furnace comprising a combustion chamber that burns fuel to cause primary combustion and a heat riser that causes secondary combustion, wherein the combustion chamber and the heat riser are arranged to communicate with each other in a substantially L-shape, in the combustion chamber, there is provided a heating pipe through which the flowing air is heated to a temperature exceeding the ignition point of the fuel by being disposed in the combustion chamber, the heating pipe has a hot air outlet from which the air heated in the combustion chamber blows out, the air blowing out from the hot air outlet has a wind pressure that blows the fuel introduced into the combustion chamber from the front side to the heat riser side arranged from the front side to the back side.

2. In claim 1, the heating pipe is formed in a substantially square shape in plan view and has an upright portion formed in a substantially L-shape in side view.

3. In claim 1 or claim 2, the fuel is RPF.

4. A combustion furnace having a rocket stove structure including a combustion chamber that burns fuel to cause primary combustion and a heat riser that causes secondary combustion, in the combustion chamber, there is provided a heating pipe through which the flowing air is heated to a temperature exceeding the ignition point of the fuel by being disposed in the combustion chamber, the heating pipe has a hot air outlet from which the air heated in the combustion chamber blows out, the air blowing out from the hot air outlet has a wind pressure that blows the fuel introduced into the combustion chamber from the front side to the heat riser side arranged from the front side to the back side, and a combustion furnace system including a cyclone that collects dust and forcibly exhausts gas, fly ash, etc. generated in the heat riser using an upward airflow.

5. In claim 4, A combustion furnace system having an ash storage section for storing collected fly ash and the like below the cyclone.

6. In claim 5, A combustion furnace system further comprising an exhaust blower for attracting hot air that has passed through the dust collector and exhausting it to the outside.

7. In claim 4, A combustion furnace system further comprising a hot water boiler including a heat exchanger for taking in hot air from the cyclone and a water storage tank.

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