JP2015209452A - Biomass fuel pretreatment method, its system, and biomass heat generation system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biomass fuel pretreatment method capable of efficiently producing biomass fuel having high combustion efficiency and having a prescribed water content, its system, and a biomass heat generation system using the same.SOLUTION: Provided is a biomass fuel pretreatment method including: a water-absorbing-drying step 20 of water-absorbing a pulverized woody material with a water-absorbing material so as to be dried; a fermentation-drying step 40 of mixing the woody material with livestock feces so as to be fermented; and a heat exhaust-drying step 50 of feeding a purification gas after gas exhaust treatment to the woody material by biomass heat generation so as to dry to a prescribed water content.

Description

  The present invention relates to a pretreatment method and system for biomass fuel suitable for biomass power generation as renewable energy, and a biomass power generation system using the same.

  In recent years, fossil fuels have been on the rise, and the amount of carbon dioxide generated by combustion is large. Therefore, interest in renewable energy, which is an alternative energy, is increasing. As renewable energy, wind power, hydropower, solar power, geothermal heat, etc. are known, but biological resources such as wood, coconut husk, animal manure, agricultural waste, etc. from the viewpoint of securing stable raw materials, regardless of weather conditions. Biomass power generation using derived materials as fuel has attracted attention as an important power generation.

The most frequently used raw materials for biomass power generation are wood materials such as demolition materials and thinned wood. However, wood materials have low energy density per unit area, variations in quality such as moisture content, and the production volume of wood materials fluctuates greatly, affecting the boiler operation plan and combustion efficiency. It has become.
Conventionally, in order to increase the combustion efficiency of a boiler, a solid fuel obtained by processing a wood material into pellets or briquettes has been used (for example, Patent Document 1).

  However, such a solid fuel has a problem that the quality of the solid fuel is stable, but the raw material is required to be pulverized in the manufacturing process, which increases the number of manufacturing processes and increases the manufacturing cost. For this reason, it is desired to produce a wooden material that is stable and inexpensive.

Therefore, in the biomass fuel pretreatment unit of Patent Document 2, steam supplied from a boiler and a part of exhaust gas generated by combustion of biomass power generation are used for heating the biomass fuel.
In addition, in the method for producing biomass of Patent Document 3, a process of aerobic fermentation in a state where wet biomass is mixed with auxiliary materials is disclosed.

JP 2012-255108 A JP 2013-88033 A JP 2011-189268 A

  However, Patent Document 2 has a problem in that energy conversion efficiency is poor because part of the steam used for power generation is used for heating the biomass fuel. Further, in Patent Document 3, there is a problem that the fermentation period extends for a long time, and when the moisture content of the initial raw material is high, it cannot be sufficiently dried by fermentation, in other words, it cannot be dried unless it is a wooden material with a certain moisture content. there were. In addition, there is a problem that substances such as activated sludge and chlorine contained in livestock manure corrode the walls and piping of the combustion apparatus.

  Furthermore, as mentioned above, wood materials produced from demolition materials, thinned wood, etc. are difficult to make a constant production amount, and it is necessary to adjust the supply amount according to the biomass power generation plan while keeping a constant amount ( Problem).

  Therefore, the problem to be solved by the present invention is to provide a biomass fuel pretreatment method and system capable of efficiently producing biomass fuel having a high combustion efficiency and a predetermined moisture content, and a biomass power generation system using the biomass fuel pretreatment method. It is said.

  Another object of the present invention is to provide a biomass fuel pretreatment method and system capable of increasing the power generation efficiency of biomass power generation, and a biomass power generation system using the same.

  The present invention provides, as a first means for solving the above-mentioned problems, a water-absorbing and drying step of absorbing and drying the pulverized wooden material with a water-absorbing material, and a fermentation and drying step of mixing animal feces into the wooden material and fermenting it. And a waste heat drying step of supplying a purified gas after exhaust gas treatment by biomass power generation to the woody material and drying it to a predetermined moisture content, to provide a biomass fuel pretreatment method.

  The present invention provides a second means for solving the above-mentioned problems. In the first means, the water-absorbing and drying step includes alternately stacking the water-absorbing material and the wooden material in a multistage manner. It is to provide a biomass fuel pretreatment method characterized in that the water-absorbing material is covered with the water-absorbing material and dried to a certain water content.

  According to the present invention, as a third means for solving the above problems, in the first or second means, the wood material and the animal manure have a total ash content of 0.2 or less of the total fuel weight, preferably Is to provide a biomass fuel pretreatment method characterized by mixing so as to be 0.15 or less.

  As a fourth means for solving the above-mentioned problems, the present invention is characterized in that the wood material and the animal waste are mixed so that the total fuel-containing chlorine concentration is 500 ppm or less, preferably 100 ppm or less. It is to provide a biomass fuel pretreatment method.

  The present invention provides, as a fifth means for solving the above-mentioned problems, a water-absorbing and drying means for absorbing and drying the pulverized wooden material with a water-absorbing material, and a fermenting and drying means for fermenting livestock dung in the wooden material. And a waste heat drying means for supplying the purified gas after exhaust gas treatment by biomass power generation to the wood material and drying it to a predetermined moisture content, for the purpose of providing a biomass fuel pre-treatment system Yes.

  The present invention provides, as sixth means for solving the above problems, the biomass fuel pretreatment system, combustion means for burning biomass fuel produced by the biomass fuel pretreatment system, and thermal energy of the combustion means And a power generation means for converting the electricity into electricity.

  According to the above configuration, long-term storage and production leveling can be performed in the water absorption drying process. That is, the biomass fuel can be produced while adjusting the drying time in accordance with the supply timing of the biomass fuel to the power generation system. Moreover, while drying time of biomass fuel can be adjusted arbitrarily, biomass fuel can be kept at the moisture content suitable for the fermentation drying process which is a next process, while storing after production.

  Moreover, since rapid drying can be performed by controlling the amount of exhaust gas supplied in the exhaust heat drying step, the amount of fuel supplied to biomass power generation can be adjusted.

  Further, a biomass fuel having a predetermined moisture content can be produced at low cost without requiring a new heating facility, a fuel cost thereof, and a pelletizing step for drying the wood material as in the prior art.

  According to the above configuration, regardless of the moisture content of the initial raw material (the moisture content of the initial raw material), for example, producing a biomass fuel having a predetermined moisture content of 40% or less, preferably 20% or less, for example. Can do.

  According to the above configuration, the wood material and the animal manure are mixed so that the total ash content is 0.2 or less, preferably 0.15 or less of the total fuel weight. The amount of generated gas can be reduced, and the load of the exhaust gas treatment facility can be reduced to realize a stable power generation operation.

  According to the above configuration, the wood material and the animal waste are mixed so that the total fuel-containing chlorine concentration is 500 ppm or less, preferably 100 ppm or less. It can reduce and can prevent the corrosion of the wall and piping of the biomass power generation system using biomass fuel.

It is explanatory drawing of the biomass fuel pre-processing method of this invention. It is a graph which shows the relationship between the size of woody material, and drying time. It is explanatory drawing of a water absorption drying process. It is a graph which shows the moisture content of each process of a biomass fuel pre-processing method. It is explanatory drawing of the biomass fuel pre-processing system and biomass power generation system of this invention.

  Embodiments of a biomass fuel pretreatment method and system and a biomass power generation system using the biomass fuel pretreatment method of the present invention will be described in detail below with reference to the accompanying drawings.

In the present invention, the biomass fuel refers to animal and plant resources such as wood, coconut husk, animal manure, and agricultural waste.
In the present invention, the woody material refers to plant biomass such as demolition material, thinning material, and pruning material.
In the present invention, livestock droppings refers to any of chicken droppings, cow droppings, pig droppings, or a mixture of two or more.

[Biomass fuel pretreatment method]
FIG. 1 is an explanatory diagram of the biomass fuel pretreatment method of the present invention. As shown in the figure, the biomass fuel pretreatment method of the present invention mainly includes a wood crushing step 10, a water absorption drying step 20, a livestock dung / wood mixing step 30, a fermentation drying step 40, and an exhaust heat drying step 50. It is configured.

[Wood crushing step 10]
The wood crushing step 10 is a step of crushing a wood material, which is plant biomass such as a demolition material, a thinning material, and a pruning material, to a predetermined size by a crusher.
FIG. 2 is a graph showing the relationship between the size of the wood material at a temperature condition of 100 ° C. and the drying time. The vertical axis of the graph represents the moisture content (%), and the horizontal axis represents time (min). When the moisture content is dried from 45% to 20% at a temperature condition of 100 ° C., as shown in the graph, it takes about 110 minutes. In addition, when drying a 30 mm size woody material from 45% to 20%, it takes about 45 minutes. Furthermore, when drying a wood material having a size of 10 mm or less from a moisture content of 45% to 20%, about 15 minutes are required. Since the surface area per unit weight of the wood material increases as the size becomes smaller in this way, the drying time can be shortened. In the wood crushing step 10 of the present embodiment, considering the drying time and the size that can be supplied to the combustion means 160 described later, the wood material is pulverized to a length of 1 mm to 100 mm, preferably 5 mm to 50 mm on the longest side. .

[Water absorption drying step 20]
The water absorption drying process 20 is a process in which a water absorption material is laid on an accumulation point (inside a container) such as a stockyard or a silo, and a wooden material crushed to a predetermined size is placed on the water absorption material to form a multilayer structure for water absorption drying. . Specifically, moisture contained in the wood material is sucked into the water absorbing material, the water absorbing material becomes a gel, and the wood material can be dried to a certain amount of moisture. The water-absorbing material of the present embodiment includes, for example, sodium polyacrylate, polyacrylate, polysulfonate, anhydrous maleate, polyacrylamide, polyvinyl alcohol, polyethylene oxide, polyaspartate , Containing a superabsorbent polymer, a superabsorbent polymer, a superabsorbent polymer, a polymer absorbent, etc., mainly composed of any one of polyglutamate, polyalginate, or a combination thereof in a sandbag, Or it formed in the sheet form. Such a water-absorbing material can be reused by drying after water absorption. In the water absorption drying step 20 of the present invention, the wood material pulverized to a predetermined size is stored on the water absorption material and dried in an atmospheric environment (for example, in the range of 10 ° C. to 40 ° C.). The water absorption drying process of the present invention can usually be carried out in an atmospheric environment. However, when there is sufficient exhaust heat in the subsequent stage, the purified gas of the exhaust gas treatment means 170 described later is supplied at the same time as the water absorption drying and the temperature is increased. You may make it wind dry. Although the drying time is not particularly limited, the input wood material can be kept dry while being dried (the drying time can be arbitrarily adjusted), so that the wood material can be adjusted according to the timing of supplying the biomass fuel to the power generation system. It is desirable to hold in the water absorption and drying process from the time of the charging until the aforementioned supply time.

  FIG. 3 is an explanatory diagram of the water absorption drying process. As shown in (1), a wooden material 24 crushed to a predetermined size is laid on the water absorbing material 22. The water absorbing material 22 is disposed thereon, and similarly, a wooden material 24 pulverized to a predetermined size is laid, and the water absorbing material 22 and the wooden material 24 are alternately laminated in multiple stages.

  As an example, when a highly water-absorbing polymer is used as the water-absorbing material 22, the wood material 24 is spread almost uniformly on a thickness of approximately 100 mm or less. As shown in (2), as a means for stacking in multiple stages, each layer is slidable, and when tilted, a dry wooden material 24 can be dropped and placed on a lower conveyor. 26 can be used.

Thereby, the water absorption drying process 20 can be performed in a space-saving manner. In addition, by arranging the wood material between the upper and lower water-absorbing materials, the contact area between the water-absorbing material 22 and the wood material 24 can be increased, the drying time can be shortened, and it is less susceptible to the humidity of the external atmosphere. Therefore, the moisture content of the wooden material 24 can be kept constant.
FIG. 4 is a graph showing the water content in each step of the biomass fuel pretreatment method. The vertical axis of the graph represents the moisture content (%), and the horizontal axis represents each step. As shown in the graph, when the moisture content of the initial raw material is 70%, the moisture content is not changed in the wood crushing step 10 and is dried to 60% in the water absorption drying step 20. The water-absorbing and drying step 20 of the present invention is mainly intended to dry the stored wood material while temporarily storing it using a water-absorbing material that is cheaper and reusable than heat drying, and is suitable for subsequent fermentation and drying. The rate is set around 60%.

[Livestock droppings / woody mixing step 30]
In the livestock droppings / woody mixing step 30, the livestock droppings are mixed with the woody material subjected to the water absorption drying step 20. Livestock droppings are any of chicken droppings, cow droppings, pig droppings, or a mixture of two or more kinds, and the mixing ratio with the woody material (livestock droppings / woody material) is 0.01 to 1, preferably 0.1 to 0. Eight. The livestock droppings / wood mixing step 30 of the present invention is not particularly limited as long as the livestock droppings and the woody material can be mixed uniformly.

  Moreover, it is desirable to mix the livestock manure / woody mixing step 30 so that the total ash content is 0.2 or less, preferably 0.15 or less of the total fuel weight. Thereby, it is possible to reduce the discharge amount of dust in the exhaust gas generated by the combustion unit 160 at the subsequent stage, and to reduce the load (the amount of exhaust gas to be processed) of the exhaust gas processing unit 170.

  Further, it is desirable that the livestock excrement / woody mixing step 30 is mixed so that the total fuel-containing chlorine concentration is 500 ppm or less, preferably 100 ppm or less. Thereby, the corrosive chlorine to an iron material etc. can be reduced and the wall of the biomass power generation system 200 and corrosion of piping can be reduced.

[Fermentation drying step 40]
Fermentation drying process 40 is a process of making it ferment in the state where livestock dung and woody material were mixed. The mixture of livestock droppings and woody material generates heat by fermentation, but it is desirable to keep the fermentation temperature at 80 ° C. or lower. This is because if the fermentation temperature exceeds 80 ° C., the wood material may spontaneously ignite. In the fermentation drying process 40 of the present invention, the fermentation time is set to about one week, and the moisture content is dried to 45% as shown in FIG. In the fermentation drying process 40 of the present invention, the water content is adjusted to about 60% through the water absorption drying process 20 in advance, so that the fermentation time is set to about 40% to 50% for about 1 week. Can do.

[Exhaust heat drying step 50]
The exhaust heat drying process 50 is a process of drying with warm air using the purified gas that has been treated with the exhaust gas in the biomass power generation system 200. The exhaust heat drying process 50 of the present invention uses purified gas that has been subjected to exhaust gas treatment by an exhaust gas treatment means 170 described later. In such a purified gas, harmful substances contained in the exhaust gas are purified, and even when used for drying biomass fuel, the harmful substances contained in the exhaust gas are not affected.

  As an example, the purified gas has a gas temperature of 100 ° C. to 160 ° C. and is supplied to an apparatus that performs the exhaust heat drying step 50. In the exhaust heat drying step 50, the moisture content can be adjusted to 20% as shown in FIG. The exhaust heat drying process 50 of the present invention can control the moisture content or the drying time by increasing or decreasing the supply amount of the purified gas. Thereby, it can match with the supply time of the biomass fuel to biomass power generation. In the exhaust heat drying step 50, the moisture content of the wood material is set to 40% or less, preferably 20% or less.

  Thereby, the biomass fuel pretreatment method of the present invention can easily control the biomass fuel to a predetermined moisture content regardless of the moisture content of the initial raw material by performing a plurality of drying steps. Moreover, even when the balance between the amount of biomass fuel accumulated and the amount used is biased and the storage amount is increased, the biomass fuel can be kept in the drying process for a long period of time.

[Biomass fuel pretreatment system 100]
FIG. 5 is an explanatory diagram of the biomass fuel pretreatment system and the biomass power generation system of the present invention. The biomass fuel pretreatment system 100 of the present invention includes a wood crushing means 110 that performs the above-described wood crushing process 10, a water absorption drying means 120 that performs the water absorption drying process 20, and a livestock dung / wood drying means that performs the animal dung / wood mixing process 30. 130, the fermentation drying means 140 that performs the fermentation drying process 40, and the exhaust heat drying means 150 that performs the exhaust heat drying process 50 are the main basic components.

  The wood crushing means 110 is a crusher that crushes a wood material into a size having a longest side of 1 mm to 100 mm, preferably 5 mm to 50 mm.

  The water absorption and drying means 120 is an accumulation point (inside a container) such as a stockyard or a silo in which a water absorbing material is laid and a wooden material crushed to a predetermined size is placed thereon to absorb and dry. Moreover, the water absorption drying means 120 can also laminate | stack a water absorption material and a wooden material alternately and in a multistage in an accumulation | aggregation location.

  The animal manure / wood mixing means 130 is an accumulation site (in a container) such as a stockyard or silo for mixing the animal manure / wood material to a mixing ratio of 0.01 to 1, preferably 0.1 to 0.8. is there. Further, it is desirable that the livestock manure / wood mixing means 130 mix so that the total ash content is 0.2 or less, preferably 0.15 or less of the total fuel weight. Further, it is desirable that the livestock excrement / woody mixing means 130 mix so that the total fuel-containing chlorine concentration is 500 ppm or less, preferably 100 ppm or less.

  The fermentation drying means 140 is an accumulation site (inside a container) such as a stockyard or silo that is fermented in a state where livestock dung and woody material are mixed.

  The exhaust heat drying means 150 is an accumulation location (inside the container) such as a stockyard or a silo that is dried with warm air using the purified gas that has been treated with the exhaust gas in the biomass power generation system 200. In addition, conveying means, such as a belt conveyor, is arranged between the various means so as to convey the wood material. Further, the exhaust heat drying means covers the conveyor surface of the belt conveyor that supplies biomass fuel to the combustion means with a casing, supplies purified gas inside, and dries the biomass material to a certain amount of moisture on the conveyor surface. It may be adopted. Thereby, it can be made to dry using a period during which biomass fuel is conveyed from the fermentation drying process to the biomass power generation system.

  Thus, the biomass fuel pretreatment system of the present invention can easily control the biomass fuel to a predetermined moisture content regardless of the moisture content of the initial raw material by performing a plurality of drying means. Moreover, even when the balance between the amount of biomass fuel accumulated and the amount used is biased and the storage amount is increased, the biomass fuel can be kept in the drying process for a long period of time.

[Biomass power generation system 200]
The biomass power generation system 200 of the present invention has a biomass fuel pretreatment system 100, a combustion means 160, an exhaust gas treatment means 170, and a power generation means 180 as main basic configurations. The biomass fuel pretreatment system 100 has the same configuration as the above-described system.

[Combustion means 160]
The combustion means 160 is a fluidized bed, a stoker furnace, or the like that can burn the biomass fuel produced by the biomass fuel pretreatment system 100. The combustion means 160 includes a heating burner (not shown) and a heat exchanger (not shown) that recovers the heat of the exhaust gas, and exchanges heat between the exhaust gas and water to generate steam that can be used for power generation. . When a fluidized bed is applied to the combustion means, the longest side of the wood material is desirably pulverized to a size of 5 mm to 50 mm.

[Exhaust gas treatment means 170]
The exhaust gas treatment means 170 has a configuration in which a reduction catalyst capable of removing harmful components and dust contained in the exhaust gas, an electric dust collector, and a desulfurization apparatus are combined. NOx and the like are removed from the reduction catalyst of the exhaust gas treatment means 170, particulate matter is removed from the electrostatic precipitator, and purified gas from which sulfur oxides are removed is released into the atmosphere by the desulfurization apparatus. A part of the purified gas treated with the exhaust gas by the exhaust gas treatment means 170 is used for drying in the above-described exhaust heat treatment process 50 (exhaust heat treatment means 150) or the water absorption drying process 20 (water absorption drying means 120).

[Power generation means 180]
The power generation means 180 converts thermal energy into electricity, includes a turbine, and generates power by rotating the turbine with steam.
Since the biomass power generation system 200 having such a configuration uses the biomass fuel having a predetermined water content produced by the biomass fuel pretreatment system 100, the combustion efficiency is good. Moreover, since the total ash content of the wood material and livestock excrement is mixed so that the total fuel weight is 0.2% or less, preferably 0.15% or less, the amount of dust generated in the exhaust gas can be reduced, and the exhaust gas A stable power generation operation can be realized by reducing the load on the processing means. Furthermore, since the total fuel-containing chlorine concentration of the wood material and livestock manure is mixed to be 500 ppm or less, preferably 100 ppm or less, chlorine that is corrosive to iron materials and the like is reduced, and the walls of the combustion means and piping Corrosion can be prevented.

  In particular, the present invention can be widely applied to a biomass power generation system that generates power using a biomass fuel obtained by mixing a woody material and livestock dung.

10 ......... Wood crushing step, 20 ......... Water-absorbing and drying step, 22 ......... Water-absorbing material, 24 ......... Wooden material, 26 ......... Rack, 30 ...... Animal dung / wood mixing step, 40 ......... Fermentation drying process, 50 .... exhaust heat drying process, 100 .... biomass fuel pretreatment system, 110 .... wood pulverization means, 120 .... water absorption drying means, 130 .... livestock dung / wood mixing means, 140. ... Fermentation drying means, 150 ......... Waste heat drying means, 160 ... ... Combustion means, 170 ... ... Exhaust gas treatment means, 180 ... ... Power generation means, 200 ... ... Biomass power generation system.

Claims (6)

A water absorption drying process in which the pulverized wood material is absorbed with a water absorbing material and dried;
A fermentation drying process in which livestock dung is mixed and fermented with the wooden material;
An exhaust heat drying step of supplying purified gas after exhaust gas treatment with biomass power generation to the wood material and drying it to a predetermined moisture content;
A biomass fuel pretreatment method comprising:   The water absorption drying step is characterized in that the water absorption material and the wood material are alternately laminated in multiple stages, and the wood material is covered with the water absorption material and dried to a certain amount of water. The biomass fuel pretreatment method as described.   The biomass fuel pretreatment according to claim 1 or 2, wherein the wood material and the animal manure are mixed so that the total ash content is 0.2 or less, preferably 0.15 or less of the total fuel weight. Method.   The biomass fuel pretreatment method according to any one of claims 1 to 3, wherein the wooden material and the animal manure are mixed so that a total fuel-containing chlorine concentration is 500 ppm or less, preferably 100 ppm or less. . Water absorption drying means for absorbing and drying the pulverized wooden material with a water absorbing material,
Fermentation drying means for mixing and fermenting livestock dung into the wooden material,
Waste heat drying means for supplying purified gas after exhaust gas treatment with biomass power generation to the wood material and drying it to a predetermined moisture content;
A biomass fuel pretreatment system comprising: A biomass fuel pretreatment system according to claim 5;
Combustion means for burning biomass fuel produced by the biomass fuel pretreatment system;
Power generation means for converting thermal energy of the combustion means into electricity;
A biomass power generation system characterized by comprising:

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