JP2009068817A - Batch type combustion boiler using woody biomass or carbide as fuel and hot air generating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boiler capable of combusting solid biomass fuel such as firewood, woody fuel, or carbide by a batch system over a long period of time, easily performing control of a combustion amount, dormancy and recombustion, and obtaining clean exhaust gas, and a hot air generating device with high thermal efficiency using the boiler. <P>SOLUTION: Clean exhaust gas is obtained by means comprising: injecting dried solid biomass fuel by the batch system into a furnace having high heat insulation properties; introducing highly concentrated flue gas generated in primary combustion to a vertical type smoke flue reaction column duct; performing secondary combustion for combusting light weight gas with preheated air; performing primary combustion for combusting flame-resistant gases and ash dust by a burner; and performing quaternary combustion for completely combusting remaining incompletely combusted portions by a honeycomb type catalyst. The combustion amount and the hot air temperature of the furnace are controlled by interlocking carbon monoxide and ash dust in the exhaust gas with combustion conditions of the primary combustion to the quaternary combustion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY In the present invention, wood and woody biomass or carbide can be burned in a batch-type combustion furnace, the amount of combustion can be controlled as necessary, and clean hot air and exhaust gas can be obtained. The present invention relates to a heating boiler and a hot air generator using the boiler.

Woody biomass fuels and carbides such as wood, pellets, and chips have been used as a useful fuel source since the history of mankind, and are attracting attention as zero-emission fuels as a measure against carbon dioxide with respect to global warming. As wood-based materials, there are known lumber mills, woodwork mills, thinned lumber, laminated lumber, building scrap, agricultural scrap, civil engineering scrap, etc., but if these can be used effectively as fuel, It is very useful for energy conservation and global warming.

At present, many methods of using wood-based fuels are known, such as wood-burning stoves, pellet boilers, and pellet generators. The method using bulk soot has the disadvantages of constantly supplying soot fuel according to the combustion state and always requiring manpower to manage the combustion according to how the soot is stacked and burned. In a large-scale wood steam engine or wood-burning stove, the fuel can be cut to about 5 to 10 cm at most and continuously supplied by mechanical means. In addition, since flue gas such as soot and carbon monoxide due to incomplete combustion is discharged, there is a disadvantage that it is difficult to take measures against environmental pollution.

The use of chips and pellet fuel has the merit that a fixed amount of fuel can be supplied, but there is a drawback that the bulk density of these fuels is low and a high heat quantity cannot be obtained. In addition, the pellet fuel has a problem that the production energy and the cost for heating and molding the pellet after chipping cannot be ignored as compared with the fossil energy. In addition, there is a problem in easily spreading the use of wood-based fuel because it causes smoke and environmental pollution with combustion.

As an improvement measure, Patent Document 1 proposes a complicated combustion system in which a first burner is installed under the support plate of the firewood in the combustion housing of the fireplace heater, and a pair of burners is further installed behind. However, there are problems that using a large number of burners is not an effective method, and that clean exhaust gas cannot be obtained. In Patent Document 2 and Patent Document 3, a method is proposed in which soot fuel is burned by a very slow method called an embedding method to suppress smoke generation. In addition to being treated, a large amount of an oxidation catalyst and a huge furnace are required to obtain a necessary calorific value, and it is difficult to extract industrially useful heat.
JP 2006-183920 A JP 2004-245563 A JP 2003-343840 A

  The problem to be solved is that when bulk wood and wood-based fuels are burned by a continuous supply method, the burning conditions can be controlled stably and burned stably, and the necessary heat generation according to the size of the scale The amount of fuel that can be obtained, but the fuel that can be used needs to be processed so that it can be continuously supplied to the furnace, and in order to stabilize the combustion conditions, the shape and quality of the fuel must be processed to be constant. There is. In addition, wood-based boilers combine facilities for effective use of heat and facilities for obtaining clean exhaust gas. There is a problem that it is more expensive than use and difficult to use.

Rather than burning large-capacity bulk wood and wood-based fuels at once, in order to burn them in batch mode over a long period of time, it is necessary to burn only a portion of the input fuel and eventually burn the entire amount . In addition, it is necessary for practical use as a combustion condition to change the combustion state freely to take out the necessary combustion heat, to suppress the heat generation to make it dormant, and to restart it, it needs to be in a reburning state. It is one of the most difficult problems for combustion technology.
Such a problem that there has never been a batch-type furnace or boiler that can freely control the combustion of the furnace, efficiently extract hot air, and keep the exhaust gas clean, or a useful small heater was there. Thus, it is desired to develop boiler technology and application devices that can be ideally burned in bulk without adding unnecessary processing and cost to the wood-based solid fuel.

In the present invention, a large amount of wood and wood-based bulk fuel or carbide is introduced into a batch furnace and burned for a long period of time. By controlling the amount of preheated combustion air, the amount of combustion and dormancy are controlled, and if necessary Using a combustion furnace with a structure that can be easily recombusted, flue gas is made into clean exhaust gas by high-temperature reactive duct, secondary gas combustion, tertiary auxiliary burner combustion, and quaternary honeycomb catalytic combustion, and high combustion The main feature is the availability of an efficient heating system.

In the boiler according to the present invention, wood and wood-based bulk fuels and carbides can be burned in a batch system for a long time, and can be used as a clean exhaust gas boiler using inexpensive main fuel and a small amount of auxiliary oil fuel. There is an advantage that a heating device suitable for generating hot air and hot water can be obtained.

A boiler capable of stably burning wood and wood-based bulk fuel or carbide according to the present invention for a long period of time, and a method of using the boiler as a warm air generating and heating device will be described below.
There is no limitation on the shape and size of the furnace that can be used, and either a cylindrical shape or a rectangular shape may be used. However, it is necessary to have a size enough to allow fuel to be burned over a target period. In order to determine the required furnace size, the total calorific value of the fuel that can be charged at one time is a good guide. The calorific value of the fuel varies depending on the type of tree, but 1 kg of dry wood corresponds to about 0.45 liters of kerosene fuel, such as kunugi, hinoki, cedar, oak, oak, lawan, beech and larch. Therefore, 1 ton of dry wood can be used as an alternative energy for about 450 liters of kerosene fuel.

In the vicinity of the furnace chamber are piping for combustion air with a preheating circuit, an air outlet 11, a smoke exhaust duct 2 at the outlet of the furnace chamber, and a smoke that short-circuits the smoke in the furnace chamber generated at the time of firing to the chimney Set up the road. The interior of the furnace chamber is often made of thick metal because of its structural strength and ease of fuel handling, but the thick metal furnace diffuses the heat of combustion and prevents local temperature rise. This hinders free burning in local locations. The furnace chamber is made of a heat insulating material, so that it is easy to raise the temperature of the combustion site and has high heat retention, so that ignition and combustion temperature can be easily maintained, and maintenance of the seed fire is also facilitated. There are features. This is one of the important factors in partially controlling the calorific value by partially burning a large volume of fuel.

In order to install a large amount of wood in the furnace, a large-diameter door that is easy to carry in to supply fuel is required, and it is also necessary to devise the installation of fuel in the furnace. In the furnace room, each piece of wood should stand vertically, and short pieces of wood can be added up. Fuel is charged until it accounts for 75-85% of the furnace volume. However, depending on the fuel preparation situation, less fuel can be used.
In the case of round materials, the gaps become large, so arrange them as close as possible to a dense structure. However, in the case of a square bar, it is important to provide a little gap so that air and combustion gas are easily convected during combustion. For example, in the case of a 15 cm square timber, a gap of about 1 cm is sufficient to avoid close contact. In addition, the top of the fuel and the front of the center are loaded with thin firewood for burning, and chips and dead branches.
Although it can be burned without installing fuel as explained above, if the amount of fuel input is small, the furnace cannot be burned for a long time or with a high calorific value. It is better to prepare fuel.

It is desirable to use a well-dried wood fuel as the fuel. The most desirable is an absolutely dry wood fuel or a charcoal such as charcoal, and the wood fuel is preferably dried to a moisture of 15 to 20 wt% or less depending on the kind of the wood. A fuel with a lot of water consumes a lot of heat before it dries and ignites, and generates a lot of moisture and smoke due to incomplete combustion. The moisture contained in the smoke will be discharged as water vapor or a high-moisture pyroligneous acid solution, but the combustion efficiency will be greatly reduced, and it will be difficult to control the combustion for ignition and extinction, so avoid the use of wet fuel It is desirable.
In order to increase the furnace temperature and promote the drying of the fuel, a part of the flue gas 16 of the chimney is mixed with the outside air supplied from the intake port of the combustion fan by opening the circulation damper 17 and supplied to the furnace chamber. It is better to promote the temperature rise and energy saving of the furnace chamber. The circulation amount of the flue gas is preferably 50% or less, more preferably 30% or less, because the amount of oxygen is small.

When the furnace chamber is ready for fuel and fueling, the ignition operation is started.点火 Since a large amount of air is required to ignite the fuel, open the small door for ignition provided on the front door, and open the flue door provided so that smoke can go straight to the chimney from the furnace chamber, The combustion air fan 10 is rotated to the maximum to introduce the maximum amount of air into the furnace chamber, and the air flow in the furnace is activated.
Next, the auxiliary burner 4 in the middle stage of the smoke exhaust duct is ignited, and the residual heat of the duct is started. After confirming the stable operation of the auxiliary burner, move on to the soot fuel ignition operation.
Furthermore, from a small window for ignition, according to the prepared lighting, the appropriate lighting such as a match, lighter, torch burner, etc. is used to ignite the lighting. After ignition, it is confirmed that the fire has burned out sufficiently, smoke has escaped into the chimney, and the soot fuel has ignited, then the ignition window is closed and the flue is closed. As a result, the smoke in the furnace chamber passes through the smoke exhaust duct to the chimney. It is good to confirm that fire has ignited the soot fuel from the observation window for the furnace chamber. If the chimney exhaust is not clean at this stage, the speed of the fan 10 is controlled to an appropriate level by the smoke sensor.

When a large amount of wood is burned in a batch manner for a long period of time by the combustion method according to the present invention, the combustion state of the fuel changes greatly with time. The combustion state after the start of sowing can be divided into an “initial combustion state”, an “open flame combustion state”, a “dormant state”, and a “reburning state”.

In the initial combustion state, only a part of the fuel is ignited by the fuel and the flames are burned up. The state of complete combustion accounts for the majority. In the initial combustion state, the generation of smoke due to incomplete combustion is large, and the smoke has a high concentration. In this state, if the rotational speed of the combustion fan 10 is increased and the combustion air is increased, the combustion is further accelerated and the generation of smoke is further increased. On the other hand, if the combustion air is reduced, the smoke is reduced due to lack of oxygen, the fire goes out and the thermal power drops.

In addition to hydrogen, methane, ethanes, carbon monoxide, etc., which are light gases that are easy to burn, smoke contains a large amount of phenols, pitches, soot, dust, etc. that are heavier than air. Phenols, pitches, soot, dust, and the like are flame retardant components that are not easily ignited and are not easily pyrolyzed. In the present invention, a combustion system for completely burning such flue gas and promoting thermal decomposition to obtain clean flue gas, and a boiler excellent in economy are provided.

In order to purify and clean the flue gas, a long vertical flue duct was installed and a high-temperature reaction tower for flue gas treatment was devised. The first of the methods is that the flue gas from the primary combustion in the furnace chamber first enters the secondary combustion section installed at the lowermost flue entrance of the flue duct 2 to increase the combustion efficiency. Secondary combustion is performed by air. The air introduced from the fan 1 into the furnace passes through the preheating pipe heated by the combustion flame and smoke in the furnace chamber, becomes high temperature and becomes the secondary combustion air, at the bottom of the flue duct. Secondary combustion is caused mainly by lightweight gases that are blown out from the nozzle 13 and easily ignited to form a “gas combustion section”. When the light gas burns, the duct temperature of the gas combustion section becomes high, and the flame retardant components such as phenols, pitches, soot, dust, etc. are heated to move to the next tertiary combustion section.

The flame retardant component phenols, pitches, soot, dust, etc., remaining in the secondary combustion section enter the high-temperature combustion box section 14 of the auxiliary oil burner, and the oil burner flame with an excess oxygen atmosphere to 900 ° C. And is strongly oxidized under stronger combustion conditions. This process is called tertiary combustion, and oxidatively decomposes flame retardant phenols, pitches, undecomposed soot and soot. This combustion process is closely related to the secondary combustion process and promotes effective thermal decomposition.
As the burner for tertiary combustion, any burner such as gas burner, kerosene burner, recycle oil burner, heavy oil burner, etc. can be used, but the one that is small and easy to use, excellent in stable operation and low fuel cost is preferred. It is done.

Although most of the flue gas undergoes oxidative decomposition after the tertiary combustion, the chemical reaction does not always occur uniformly in the reaction field by the flame, and some unreacted parts and undecomposed parts are likely to remain. Therefore, the unburned portion resulting from the tertiary combustion needs to be subjected to a more precise and strict heat treatment in the fourth combustion process. For this purpose, the flue gas is passed through a fine reaction cell of a ceramic honeycomb oxidation catalyst that has become hot, so that it can be burned uniformly, pyrolyzed, and even a small amount of flame-retardant components can be burned completely. Thus, the reaction temperature, reaction field, and catalyst performance were devised.
High-temperature exhaust gas that has undergone secondary combustion to quaternary combustion enters the Finchub heat exchanger, heats the outside air, rapidly decreases in temperature to 200 ° C. or less, and is discharged from the chimney. By this mechanism for rapidly cooling the exhaust gas, dioxins that are easily generated when phenols and halogens are mixed in the fuel can be safely pyrolyzed.

The use of catalysts is known to purify oily smoke, organic solvents, carbon monoxide, odors, etc., but wood-based exhaust smoke can be used to remove hydrocarbons, phenols, pitches, oily smoke, carbon, dust, etc. A large amount is included, and there are many more difficult problems to purify these than the exhaust gas treatment of diesel engines. However, as described below, by using a heat-resistant honeycomb catalyst, a uniform high-temperature reaction field could be secured, and high-concentration oil smoke, soot and soot at a high temperature of 700 to 800 ° C. and in an oxidizing atmosphere. Dust was able to be purified. As such a heat-resistant honeycomb catalyst, a SiC honeycomb filter with low pressure loss is known for diesel engines. However, a catalyst honeycomb made of metal oxide is economically useful as one of the catalysts useful for this purpose. It is. As an example, NA NA Honeycomb manufactured by Nagamine Seisakusho can be mentioned.

In the flue gas in the initial combustion process with a high flue gas concentration through the primary combustion to the quaternary combustion process, carbon monoxide was suppressed to 10 ppm or less and the soot concentration was suppressed to 0.1 g / Nm ³ or less. The environmental standard carbon monoxide by the Air Pollution Control Act is 10 ppm or less, and the soot emission standard of heavy oil boilers (40,000 Nm ³ / h class with much exhaust gas compared to the boiler) is 0.30 g / Nm ³ ( General area). As described above, in the biomass boiler according to the present invention, clean exhaust gas having a value equal to or less than a specified numerical value required as an environmental standard can be obtained.

If the supply amount of combustion air to the furnace exceeds the limit, the smoke becomes high concentration, and a complete combustion state cannot be obtained even after passing through the smoke exhaust duct, and carbon monoxide, pitches, soot, etc. are discharged from the chimney. Cause. In this case, since the furnace exceeds the combustion capacity and exceeds the flue gas purification limit of the duct, it is necessary to suppress the supply amount of the combustion air.

When the smoke emission from the chimney is monitored with an optical sensor and the amount of soot and carbon monoxide exceeds the reference value, the combustion is regulated as the maximum combustion amount assuming that the upper limit of the furnace capacity is reached. In this case, since the speed of the intake fan has reached the allowable maximum value, it is possible to satisfy the clean smoke exhaustion condition by reducing the speed to reduce the combustion air and the combustion amount. Further, the combustion amount, that is, the speed of the combustion fan is controlled based on the difference between the temperature of the hot air and the set temperature. By setting the allowable maximum speed of the combustion fan as the limit of the temperature rising speed, a control system necessary for obtaining stable combustion conditions and clean exhaust gas can be completed.

If the initial combustion state with a lot of smoke continues for 24 to 36 hours, the furnace shifts to the open fire combustion state. In this state, the surface of most of the soot fuel is carbonized, and when it hits the air, it is easily reddish and combusted, and it becomes a mixed state of charcoal combustion and soot combustion, and later, The ratio will increase and the generation of oil smoke and soot will decrease. For this reason, the carbon monoxide component increases in the open flame combustion, but the amount of soot is small and it is easy to clean the flue gas. The secondary combustion gas decreases, the temperature of the gas combustion section decreases, and the flue gas becomes clean, so the use of the auxiliary burner for tertiary combustion is intermittent and the usage time is halved. The temperature is desirably about 700 ° C. or higher. Thus, in the open flame combustion state, clean exhaust gas can be easily maintained through the secondary combustion, the tertiary combustion, and the quaternary combustion related to the above-described flue gas treatment.

When the combustion amount of the furnace is lowered and the temperature difference of the hot air is increased by several degrees C. compared to the outside air, the amount of combustion air blown becomes small. In this case, the auxiliary burner is stopped and the exhaust gas is often kept clean by secondary combustion in the gas combustion section and quaternary combustion by the catalyst.

Next, a dormant state that minimizes the heat output of the furnace will be described. In using the boiler according to the present invention, whether or not the heat output can be controlled is one of the important factors. Electricity, gas fuel, petroleum fuel, and the like can be repeatedly ignited and extinguished when necessary, but a boiler using a batch type solid fuel cannot repeat combustion and extinguishing in a short time. Therefore, the function of putting the combustion state of the furnace to sleep or reburning is a very important function.

In both the initial combustion state and the fire combustion state, the furnace chamber is at a positive pressure, and when the combustion air fan is stopped, the flue gas flows backward through the fan. When the rotational speed of the fan is adjusted so as to overcome this reverse flow and sufficient time has passed, the fan approaches the minimum speed or stopped state after 30 to 60 minutes, for example. Further, by keeping the operation of the fan 10 at the minimum speed, the furnace can enter a dormant state and can remain dormant until combustion air is supplied into the furnace later. In this way, the fire type is preserved by continuing a slight inspiration during the dormant state of the furnace, and recombustion can be easily performed if combustion air is supplied when necessary. However, if the dormant time is prolonged for many days, the fire type is maintained but becomes small, so it tends to take time to burn up at the time of reburning. When the effect of reburning is desired in a short period of time, it can be rapidly reburned by adding a burner that is easy to burn.

The method of generating and taking out hot air is important. Two flow paths are provided that allow the outside air to be sucked in from the ceiling opening 20 of the furnace with the hot air fan 8 and heated at the furnace chamber periphery 201 and the duct periphery 202. In general, the surface temperature of the furnace chamber is different from the surface temperature of the duct and the amount of heat exchange. Therefore, in order to balance the amount of heat, the partial flow rate of the outside air is adjusted by a damper 18 installed at the upper rear part of the furnace chamber.

The outside air heated at the furnace chamber ceiling is further heated through a furnace tube heat exchanger on the side of the furnace, reaches the lower part of the side of the furnace chamber, and becomes hot air 201 at 100 ° C. or lower. The hot air 201 is mixed with the mixing outside air 22 taken from the louver 22 in front of the furnace body to become hot air 220 having an appropriate temperature. On the other hand, the outside air 20 heated in the furnace chamber ceiling portion becomes hot air 202 through the exhaust duct portion and is mixed with the outside air 21 sucked from the damper 211 on the side surface of the duct to become hot air 210 having an appropriate temperature. It is supplied to the outside of the furnace by the fan 8.

When the hot air fan 8 is stopped, the furnace has a heat storage action, and the surface temperature of the furnace chamber and the surface temperature of the duct rise abnormally. In order to prevent the occurrence of such an abnormal temperature rise due to heat storage, the warm air fan 8 is always moved to prevent abnormal temperature rise. That is, the warm air fan 8 has a normal operation mode during combustion when generating warm air and an idling operation mode during non-combustion when the air volume is small, and the generated warm air is discharged outside the furnace in the idling mode. It was found that stable furnace temperature and warm air can be easily maintained by preventing heat storage in the furnace.

Energy distribution when a kerosene burner is used for secondary combustion will be described. If the fuel input to the furnace is 1,000 kg per batch and burning for 10 days per batch, the calorific value is 400,000 kcal per day. This amount of heat corresponds to a daily amount of 45 L in terms of kerosene. The oil consumption of the auxiliary burner is assumed to operate the furnace for an average of 12 hours a day, and the kerosene is burned intermittently with an average ignition time of 50% using a small kerosene burner (1.5 liters / hour). Will use about 1.5L / hx 12h x 0.5 = 9L per day. Therefore, dredged fuel can replace 45 / (45 + 9) = 83% of the amount of heat with respect to the total amount of heat generated by the small furnace (1,000 kg / batch). In the case of a medium-sized furnace (2,000 kg / batch), the total amount of heat generated by soot is equivalent to 90 L per day in terms of kerosene, and the same small burner can be used, so 91% is replaced by soot fuel. Thus, the solid biomass boiler of the present invention has a great alternative effect in the energy field.

The combustion period of the furnace depends on the amount of fuel consumed. Because it depends on the heating temperature and the size of the house to be heated, it is better to make a judgment based on the amount of heat energy equivalent to kerosene. 500-800 kg of soot fuel was burned for 10 hours a day, and the fuel could be operated freely for 7 days, 10 days, and 20 days per batch depending on the calorific value.
When using the boiler or the hot air generator, the wood vinegar and wood ash are collected at the furnace low. Although the amount of wood vinegar depends on the tree species and dry state, about 10 liters per ton of well-dried building material was obtained. Moreover, when the furnace is burned for one batch, 1-2% by weight of fuel is accumulated in the ash collecting tray at the bottom of the furnace. Wood vinegar is used for disinfecting greenhouses and cultivated land, and wood ash is used as fertilizer.

Biomass boilers and hot air generators according to the present invention are used for agriculture such as green houses, plastic houses, livestock barns, industrial facilities such as drying facilities, public facilities such as hospitals, nursing homes, schools, nurseries, and houses in cold regions. It is expected to be used flexibly for heating such as work place and snow melting.

Measuring method Combustion exhaust gas components are measured by using a combustion management tester SEM-103 of Komyo Chemical Co., Ltd., gas temperature [0-1200 ° C], oxygen (0.0-22.0%), carbon monoxide. (0 to 2000 ppm) and nitric oxide (0 to 2000 ppm) were measured. The dust concentration was determined from the baccarat index by using a smoke tester (KANE MSP) and the amount of dust according to JIS Z 8808 method.

Hereinafter, the present invention will be described more specifically based on examples. However, the contents described below are merely examples, and the present invention is not limited to the contents described below.

FIG. 1 is a conceptual diagram of a boiler for burning wood or woody biomass or carbide fuel according to the present invention and a warm air heating device having a function of generating warm air.

Furnace room 1 has a volume of 1.1 m ³ , and about 700 kg of fuel was used as dry building scraps of 5 and 10 x 10 square timber, which is wood for building materials. A cocoon of about 3 to 5 cm in thickness for the same material was placed in the upper center of about 2 kg, and a twig and several old newspapers were placed between these caskets, and the front furnace chamber door was closed.

First, the suction fan 10 was set to the maximum speed, the maximum amount of combustion air was introduced into the furnace chamber, the flue that becomes a short circuit connecting the furnace chamber and the chimney was opened, and the flow of air in the furnace was activated. Next, the auxiliary burner is ignited and the residual heat of the duct is started. After confirming the stable operation of the burner, the ignition window on the furnace chamber door was opened, and the cassette gas torch burner was used to ignite it. While waiting for the fire to spread in the furnace and ignite the soot, the auxiliary burner 4 in the middle stage of the smoke exhaust duct is ignited, the catalyst 7 and the duct provided in the upper stage of the burner box are preheated, and the soot is ignited. After confirmation, the small ignition window was closed and the flue was closed.

Combustion air 11 from the combustion air fan promotes combustion of soot fuel in the furnace, but in the initial combustion state in the early stage of ignition, the temperature of the furnace body, and thus the temperature of the soot and the soot drying state are not sufficiently advanced. Therefore, it is necessary to maintain the combustion state as it is for about 10 to 15 minutes until the combustion becomes stable. If the strength of the flue gas is maintained, the ignition will be a good guideline. At this time, the smoke coming out of the chimney is usually dark enough to be visually recognized, so the speed of the combustion air fan is immediately reduced to a steady value (˜50% capacity), and the secondary combustion temperature of the gas combustion unit 13 is 600 to 8500 ° C. The speed of the combustion air fan was lowered so that the quaternary combustion temperature of the catalyst combustion section 15 would be 700 to 8500C. By this operation, the flue gas 16 in the chimney became transparent to the extent that it cannot be seen. During this time, 20 to 30 minutes had elapsed since ignition.

The flue gas burned at a high temperature in the exhaust duct reaches the fin tube heat exchanger 5 through the horizontal connection duct 15, and is quickly cooled and discharged to the chimney 6. The discharge temperature to the chimney was 100 ° C to 150 ° C. The low smoke emission temperature indicates that the combustion heat is efficiently used to heat the outside air, and that the combustion heat is converted into hot air with high efficiency.

The following shows measured values of the exhaust gas temperature and exhaust gas components from the chimney in the initial combustion state 4 hours after the most severe ignition to obtain clean exhaust gas.
Secondary combustion temperature: 834 ° C, Fourth combustion temperature: 792 ° C, Outside air: 25 ° C, Hot air: 40 ° C,
Chimney exhaust: 104 ° C,
Oxygen: 20.4%, CO: 0 ppm, NO: 0 ppm, dust: <0.06 g / Nm ³

When the hot air fan 8 (maximum rating 3000 m ³ / h) is driven, outside air of about 20 ° C. flows from the suction hole 20 in the center of the furnace chamber ceiling and is heated by the furnace chamber ceiling surface 201, and a part of the fin The tube 5 was further heated to become hot air of about 70 ° C., and part of the air was heated on the duct surface to become hot air. Each hot air was mixed with outside air 21 & 22 along the way, and was supplied to the outside of the furnace as warm air 25 of about 40 ° C. The temperature of the hot air is determined by the amount of combustion in the damper 20 of the suction hole and the furnace, and the temperature of the hot air is determined by the mixing amount of the hot air and the outside air. A structure in which the opening / closing amounts of the mixing dampers 22 & 211 can be adjusted automatically and manually was used.

Comparative Example 1
In order to investigate the secondary combustion effect, the preheated combustion air to the gas combustion burner for secondary combustion was stopped and the operation was continued. As a result, the carbon monoxide in the exhaust gas increased to 5 ppm and the amount of dust increased to 0.1 g / Nm ³ .

Comparative Example 2
In order to investigate the effect of the auxiliary burner in the tertiary combustion section, the ignition of the auxiliary burner was stopped and the combustion operation was continued. As a result, after 30 minutes, the temperature of the burner box part and the catalyst part of the tertiary combustion part decreased, the clogging of the catalyst progressed, and the duct function was impaired.

Comparative Example 3
In order to investigate the effect of the quaternary combustion section, the catalyst for quaternary combustion 7 was removed and a combustion operation was performed. As a result, the carbon monoxide in the exhaust gas increased to 10 ppm, and the dust increased to 0.1 g / Nm ³ .

  The temperature of exhaust gas from the catalyst in the quaternary combustion section is 700 ° C or higher, but the temperature of the exhaust gas will be 200 ° C or lower when leaving the heat exchanger, and it will be cooled rapidly in the fin tube. all right.

In this way, the solid combustion combustion exhaust gas is cleaned by going through the primary combustion 12 in the furnace, the secondary combustion 13 at the lowermost part of the reactive duct, the tertiary combustion 14 by the auxiliary burner, and the quaternary combustion 15 by the honeycomb catalyst. A system that can produce a simple exhaust gas was obtained. When it was in the open flame combustion state, the smoke concentration of the exhaust gas was greatly reduced, and the ignition time of the auxiliary burner was greatly shortened, and the batch average was about 50%.
When halogen ions such as phenols coexist, there is a risk of dioxin formation, but in this case as well, there is a system in which exhaust gas that has undergone sufficient high-temperature decomposition can be obtained through a heat exchanger of Fintub to obtain safe and clean exhaust gas. It was constructed.

The boiler and hot air generator according to the present invention safely burns inexpensive wood-based solid fuel, especially lumber mill edge, woodwork mill edge, laminated lumber edge, waste building material, thinned wood, etc. In addition, it can contribute to solving environmental problems of waste materials and is expected to be used as an environmentally friendly heating device that can naturally circulate greenhouse gases.

According to the present invention, instead of petroleum-based fossil fuel, as an boiler capable of burning inexpensive wood-based solid fuel in a batch system, an agricultural plastic greenhouse, a green house for flower cultivation, a public bath, a hospital, a nursing home It is expected to be widely used for schools, meetinghouses, livestock farms, barns, drying grounds, and snowmelts.

Structural conceptual diagram of a hot air generator combined with a batch-type combustion boiler that can produce clean exhaust gas by burning wood solid biomass fuel such as firewood, wood fuel or carbide of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace 2 Duct 3 Burner box 4 Burner 5 Fin tube heat exchanger 6 Chimney 7 Honeycomb catalyst 8 Warm air fan 10 Fan for combustion air 11 Combustion air 12 Furnace combustion air 13 Secondary combustion nozzle and secondary combustion Part 14 Tertiary combustion part 15 Exhaust after the fourth combustion 16 Flue gas 17 Flue gas circulation part 20 Outside air introduction part 1
21 Outside air introduction part 2
22 Outside air introduction part 3
201 Furnace Chamber Surface Air Curtain Flow 220 Furnace Chamber Surface Hot Air 202 Duct Surface Air Curtain Flow 210 Duct Surface Hot Air 25 Hot Air Supply Unit

Claims (7)

It is a furnace that burns wood-based fuels or carbides in a batch system. In this combustion furnace, an initial combustion state showing a high degree of incomplete combustion and a fire-burning state showing a slight incomplete combustion due to progress of carbonization of the fuel. Regardless of this, it is possible to control the combustion and heat generation by controlling the supply amount of preheated combustion air, and to be able to stay in a dormant state at the time of minimum combustion and to maintain the fire type for recombustion. A biomass heating boiler and its structure. In the heating boiler, the primary combustion chamber is constituted by a furnace wall having high heat insulation properties, and a vertical reaction duct for treating high-concentration flue gas generated by the primary combustion is connected to the smoke exhaust port. A lightweight gas combustion burner that burns with preheated air for secondary combustion is installed at the entrance, and an auxiliary burner and combustion box section that burns flame-retardant gases and soot is installed in the middle stage of the duct, Furthermore, a flue gas purifying structure characterized in that a combustion part by a honeycomb type oxidation catalyst is installed at the uppermost stage of the duct for quaternary combustion.     The reaction duct has a low heat capacity and has a heat retaining structure that can easily be raised to 800 ° C. or higher, and the high-temperature exhaust gas that has passed through the reaction duct is rapidly cooled to 200 ° C. or less via a heat exchanger that heats the outside air. A biomass heating boiler characterized by being discharged from a chimney as a clean exhaust gas with little carbon monoxide and dust. The low-temperature outside air is supplied from the suction port of the furnace body ceiling, heated by the furnace chamber surface, duct surface, and heat exchange, and then mixed with the outside air to supply hot air at an appropriate temperature. A feature of hot air generation. The hot air supply fan has a normal operation mode for generating hot air and an idling operation mode with at least a small air volume. In the idling mode, the generated hot air is discharged outside the furnace to prevent heat accumulation in the furnace. A method for supplying warm air, characterized in that the temperature can be stably maintained. The exhaust gas in the boiler chimney is monitored for carbon monoxide gas and dust components by an optical sensor, and the output of the sensor can control the amount of combustion air by an intake fan and tertiary combustion by an auxiliary burner. , Combustion and smoke control mechanism.   A combustion mechanism characterized in that a part of the flue gas of the chimney is mixed with the outside air supplied from the intake port of the combustion fan and supplied to the furnace chamber to contribute to the temperature rise and energy saving of the furnace chamber.