JP2005291536A - Crushing method and device of biomass fuel, and combustion method and equipment of biomass fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crushing method and a device of biomass fuel capable of stably supplying woody biomass fuel without a seasonal change; and a method and an equipment used for combustion by using provided biomass fuel. <P>SOLUTION: The woody biomass fuel is crushed to at least two stages or more from a chip state, and is formed in the grain size of 3 mm or less, and the biomass fuel is provided by mixing and crushing a woody pellet before crushing of the final stage. Thus, since the woody pellet superior in crushing performance is used separately from a woody chip for reducing crushing motive power of the woody biomass fuel, even if an available quantity of the biomass fuel is seasonally changed, the woody biomass fuel can be stably provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method and apparatus for pulverizing biomass fuel, and a combustion method and apparatus that realizes CO ₂ emission reduction by burning the biomass fuel with low NOx and high efficiency.

  Biomass fuel as used in the present invention is a plant-based fuel other than fossil fuels, and the type thereof is not limited to a specific one. It shall mean a plant-based fuel having a calorific value that can be a fuel containing a next processed product.

In recent years, wood-based biomass co-firing technology has attracted attention as one of the measures to reduce CO ₂ emissions in boilers that use fossil fuel as the main fuel.
Particularly in Europe and North America, woody biomass fuel is often mixed with coal in an existing coal pulverizer, mixed and pulverized, and then supplied together with pulverized coal into a coal-fired boiler furnace for combustion. Yes. As woody biomass fuel, what has been pulverized in advance before being transported to the location of the boiler, so-called pelletized, and wood chips that have been pulverized to about 50 mm or less are in circulation. As another example of co-firing, many techniques have been performed in which woody biomass fuel is finely pulverized by a dedicated pulverizer and then mixed into a pulverized coal conveyance line and mixed in a furnace. In recent years, wood biomass fuel co-firing technology has attracted attention as one of the measures for reducing CO ₂ emissions particularly in coal-fired boilers.
Japanese Patent Laid-Open No. 2002-241761

  As described above, when pelletizing woody biomass fuel, the pulverization power in the process of pulverizing and producing pellets is very large. It is known that 10 times or more power is required to obtain the same particle size as compared with the pulverization power required for coal used in a coal-fired boiler of a normal thermal power plant. For example, in coal, when a roller mill is used as a pulverizer, it is 10 to 20 kWh / t, whereas when biomass fuel is used as an impact mill (used most for pulverizing biomass fuel) as a pulverizer Usually, it is 100 to 200 kwh / t. However, since the biomass fuel is easier to burn than coal if it has the same particle size, the pulverized particle size can be coarsened. That is, in the pulverization of biomass fuel, it is preferable in terms of operation that the pulverized particle size is coarsened to a combustible limit.

  Next, there is a problem concerning the supply situation of woody biomass fuel. That is, the supply amount of woody biomass fuel depends on the discharge conditions such as thinned timber and sawmill waste, and is highly seasonal and difficult to receive a stable supply as biomass chips.

  An object of the present invention is to provide a method and apparatus for pulverizing biomass fuel that can stably supply woody biomass fuel without seasonal variation, and a method and apparatus for use in combustion using the obtained biomass fuel.

In the present invention, the above problem is solved by the following means.
According to the first aspect of the present invention, the woody biomass fuel is pulverized into at least two stages or more from the chip state to a particle size of 3 mm or less, and the woody fuel is mixed with the woody pellets before the final stage of pulverization Is the method.

  The invention according to claim 2 includes two or more pulverizers for pulverizing the woody biomass fuel into at least two stages from the chip state, means for supplying the woody pellets to the pulverizer before the final stage, and the wood system This is a biomass fuel pulverization apparatus provided with means for mixing at least one of wood chips, sawn wood waste, and thinned wood into pellets.

  The invention according to claim 3 is the combustion of biomass fuel that is obtained by using the biomass fuel obtained by the method for pulverizing biomass fuel according to claim 1 as a secondary fuel and supplying coal into the furnace together with combustion air as the main fuel. Is the method.

  The invention according to claim 4 is a biomass comprising means for supplying coal as a main fuel to a furnace and means for supplying biomass fuel obtained by the method for pulverizing biomass fuel according to claim 2 as a secondary fuel to the furnace. It is a fuel combustion device.

  The invention according to claim 5 is the biomass fuel combustion apparatus according to claim 4, wherein the furnace is a boiler furnace for generating steam.

  According to the first and second aspects of the present invention, wood pellets having excellent pulverization properties are used separately from the wood chips in order to reduce the grinding power of the wood biomass fuel. Woody biomass fuel can be obtained stably even if there are seasonal fluctuations.

According to the third and fourth aspects of the invention, since the pulverized biomass fuel can be used as a secondary fuel and coal can be used as a main fuel for combustion in a furnace, when combustion using a woody biomass fuel becomes possible stably At the same time, the in-furnace denitration effect can be enhanced, contributing to high efficiency, safety and CO ₂ emission reduction (preventing global warming).

Embodiments of the present invention will be described with reference to the drawings.
In this embodiment, first, attention is paid to the use of wood pellets excellent in grindability in addition to the wood chips in order to reduce the grinding power. For this purpose, in order to cope with unstable factors such as seasonal fluctuations, the temperature and humidity were controlled by silos etc. for the long-term storage of the pellets by providing means for primary storage of pellets in the power plant premises. A safe storage means is required.

FIG. 1 shows a pulverization technique for biomass fuel used as an auxiliary fuel for a coal fired boiler according to the present invention.
The woody biomass fuel is transported from the outside to the power plant yard by land transportation or by a biomass tanker, and is primarily stored in the biomass storage 1 such as a fuel yard. Indoor storage is desirable for safe long-term storage. Next, when accepting logs or branches and leaves as thinned wood, it is crushed into wood chips of about 50 mm under by a chip making device such as a tab grinder 2. In FIG. 1, the tab grinder 2 can be bypassed when biomass fuel is received in the form of chips.

  Next, since metal pieces such as nails are often mixed in the bulk at the stage of being thinned and carried, foreign materials are removed using the magnetic separator 3. However, since there are many remaining in the bulk state, it is desirable to install a plurality of magnetic separators 3 at each important point in the pulverization process. In FIG. 1, it is also provided on the upstream side of the hammer mill 6 in the post process.

  Chip-shaped biomass fuel is sent to a fixed-feed feeder 4 with a hopper for primary storage, and when used for combustion, a certain amount of biomass fuel chip is supplied to a hammer mill 6 as a crusher via a conveyor 5. To do. The hammer mill 6 is an impact type pulverizer, and can roughly pulverize a received chip having an under 50 mm to an under 20 mm to 10 mm. Further, the impact mill 7 suitable for fine pulverization is pulverized to the target particle size (under 3 mm) by the same impact type pulverizer, and then supplied to a burner facing a boiler furnace (not shown) by airflow conveyance. It is co-fired with coal. In FIG. 1, after being collected from the impact mill 7 through the bag filter 8, it is supplied to the burner by airflow conveyance.

  On the other hand, the pellet-shaped biomass fuel is stored in the pellet silo 9, and the necessary amount is supplied to the outlet of the hammer mill 6 by the conveyor 5 and merged with the chips coarsely pulverized to 20 mm to 10 mm under by the hammer mill 6. A certain amount is supplied to the impact mill 7 by the feeder.

  FIG. 7 is a graph showing the relationship between the mixing ratio of the pellet-shaped biomass fuel mixed in the chip and the pulverization power unit in the case of the configuration shown in FIG. FIG. 7 is a characteristic value when the particle size of the product finally crushed by the impact mill 7 is fixed under 3 mm. When the pellet mixing ratio is 100%, that is, when only the pellet is crushed, the pellet mixing ratio is 0. %, That is, the processing capacity is about 10 times that of the case where only the chips are crushed.

  FIG. 2 shows a simple system for supplying biomass fuel fine powder directly to the boiler without passing through the bag filter 8 as compared with the system of FIG. FIG. 3 shows a case where the pellets stored in the pellet silo 9 are fed into the fixed amount feeder 4 on the upstream side instead of the downstream side of the hammer mill 6. In this case, the pellets and chips are put into the fixed amount feeder 4. Since it mixes, there exists an advantage which can skip the fixed_quantity | feed_rate of the pellet from the pellet silo 9 like FIG.

  FIG. 4 is a simplified system excluding the bug filter 8 of FIG. FIG. 5 shows a case where only the pellets are supplied with the chip supply stopped in the system of FIG. The shaded area in FIG. 5 is the operating device range. The feature in this case is that the biomass supply amount can be about 10 times that when only chips are supplied by using a pulverization system with low pulverization power, so that the system can easily cope with an increase in the biomass co-firing rate. Is possible. As a case where an increase in the co-firing rate is required, for example, when further NOx reduction is required at the boiler outlet, or when coal fuel that requires countermeasures against unburned fuel is burned as the main fuel, NOx is not obtained only with normal coal combustion. When the reduction of the value must be sacrificed, increasing the co-firing rate of the biomass fuel can increase the in-furnace denitration effect and prevent an increase in the unburned amount without sacrificing further low NOx combustion or NOx value The advantages such as FIG. 6 shows a system excluding the bug filter shown in FIG.

The present invention can stably obtain a woody biomass fuel even if there is a seasonal variation in the amount obtained, and also uses the obtained woody biomass fuel to reduce CO ₂ emissions with a high denitration effect (global warming). It can be used for a combustion apparatus that contributes to prevention of conversion.

It is a highly efficient woody biomass pulverization supply combustion system of the present invention. Among the highly efficient woody biomass pulverization supply combustion system of the present invention, it is a system for supplying product biomass fine powder directly to a burner. Of the high-efficiency wood biomass pulverization supply combustion system of the present invention, the wood pellets are supplied to the former mill of the two-stage pulverization system and pulverized. Of the high-efficiency woody biomass pulverization supply combustion system of FIG. 3, the product bio fine powder is directly conveyed to the boiler and burned. In the system for simultaneously pulverizing and supplying wood pellets and wood chips of the present invention, the pellets are pulverized mainly, collected in a bag filter, and then supplied to a boiler furnace for combustion. In the simultaneous pulverization supply system of the wood pellets and the wood chips of the present invention, the product bio fine powder is directly supplied to the boiler combustor. It is a graph which shows the relationship between the mixing ratio which mixed the pellet-shaped biomass fuel in the case of the structure shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Biomass storage place 2 Tab grinder 3 Magnetic separator 4 Fixed supply feeder 5 Conveyor 6 Hammer mill 7 Impact mill 8 Bag filter 9 Pellet silo

Claims (5)

  A method for pulverizing biomass fuel, comprising pulverizing a woody biomass fuel into at least two stages from a chip state to a particle size of 3 mm or less, and mixing woody pellets before pulverization in the final stage. Two or more pulverizers for pulverizing the woody biomass fuel into at least two stages from the chip state;
A means for supplying wood pellets to a pulverizer before the final stage, and means for mixing at least one of wood chips, sawn wood waste, and thinned wood into the wood pellets are provided. Crushing equipment.   A method for combusting biomass fuel, characterized in that the biomass fuel obtained by the method for pulverizing biomass fuel according to claim 1 is used as a secondary fuel, and coal is used as a main fuel to be supplied into a furnace together with combustion air for combustion. Means for supplying coal as the main fuel to the furnace;
Means for supplying biomass fuel obtained by the method for pulverizing biomass fuel according to claim 2 to a furnace as a secondary fuel;
A biomass fuel combustion apparatus comprising:   The biomass fuel combustion apparatus according to claim 4, wherein the furnace is a boiler furnace that generates steam.

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