JP6745524B2 - Tar removal method for biomass dry distillation gas power generation system - Google Patents

Description

The present invention relates to a biomass dry distillation gas power generation system in which tar is removed from a gas obtained by heat-treating a biomass raw material (hereinafter referred to as “biomass dry distillation gas”), and then a power generator that uses the gas as a power source generates power. Related to the method for removing tar.

In recent years, combustible pyrolysis gas (biomass carbonization gas) obtained by pyrolyzing a biomass material in a pyrolysis furnace or a gasification furnace is burned in a heat engine such as a gas engine or a gas turbine to generate heat only. Cogeneration systems that have been able to generate electricity without any attention are drawing attention. However, tar is contained as a by-product in the biomass carbonization gas. This tar causes clogging of the pipe and malfunction of the heat engine, resulting in deterioration of the heat energy recovery efficiency. Then, in the conventional method and the system, a large amount of equipment investment and maintenance cost are required for removing the tar, which has a great adverse effect on the profitability of the system.

A method for removing tar or a system or apparatus for removing tar in such a cogeneration system is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-253274 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2003-277773 ( It is disclosed in Patent Document 2). In the systems of Patent Documents 1 and 2, tar is obtained by bringing biomass dry distillation gas into contact with an organic refrigerant (Patent Document 1) and a solvent such as light oil, kerosene, benzene, xylene, and toluene (Patent Document 2) to clean the tar. Is to remove.

Further, regarding the tar removal related to the biomass carbonization gas, in addition to the solvent cleaning as in Patent Documents 1 and 2, for example, the condensed tar as disclosed in JP-A-2005-60533 (Patent Document 3) is filtered. Or a method of removing it using a porous catalyst, or adding (adding) an oxidant such as oxygen to condensed tar as disclosed in JP 2008-24752 A (Patent Document 4). ) And decomposed by high temperature pyrolysis, and the decomposed tar content is further adsorbed by an adsorbent and removed.

JP, 2003-253274, A Japanese Patent Laid-Open No. 2003-277773 JP 2005-60533A JP, 2008-24752, A

However, in the inventions of Patent Documents 1 and 2, when an organic refrigerant, petroleum gas oil or kerosene, and aromatic hydrocarbons such as benzene, xylene, and toluene are used as the cleaning agent, they themselves generate tar. Since it contains it, tar cannot be removed.

Further, since the method described in Patent Document 3 performs the treatment at a high temperature of 1100° C., it requires a large amount of equipment investment and maintenance cost. Further, after the tar treatment, it can be cooled to room temperature as a power generation material. There was no choice but to lose heat, so there was a big economic problem. Further, in the method described in Patent Document 4, although heat is not lost as compared with the method described in Patent Document 3, equipment for oxidation treatment, equipment for adsorption removal, and installation of a filter in addition to them As a result, the system becomes complicated, and there are cases where capital investment and maintenance costs are required. Further, in Patent Document 4, since the tar content is physically removed, there is a possibility that a slight amount of tar content remains in the pipe or the like.

In view of the above, there is provided a tar removal method according to a biomass dry distillation gas power generation system in which tar is removed from a gas (biomass dry distillation gas) obtained by heat-treating a biomass raw material, and then the gas is used to generate power.

A tar removal method according to a power generation system for biomass carbonization gas according to the present invention, which aims to solve the above-mentioned problems, includes a pyrolysis step of pyrolyzing and carbonizing a biomass raw material, and a biomass carbonization gas separated in the pyrolysis step. A washing/cooling step of washing and cooling the biomass, a step of storing the biomass dry distillation gas washed in the washing/cooling step, and a step of using the biomass dry distillation gas as a power source of a generator, wherein the thermal decomposition In the step, the biomass raw material is pyrolyzed at 10 to 20 kg per hour, and the carbonization temperature is 450 to 550° C., and in the pyrolysis step, superheated steam is further used in combination, and the superheated steam is used. Has a temperature of 500 to 700° C., a pressure of 100 to 300 mmH ₂ O, and in the washing and cooling step, the biomass carbonization gas is washed with vegetable oil or biodiesel fuel, and up to 20 to 40° C. It is effectively cooled by cooling the vegetable oil to a temperature of 2 to 5 kg/cm ² for circulation .

Further , the configuration of the tar removal method according to the power generation system of biomass carbonization gas according to the present invention, the vegetable oil, rapeseed oil, sesame oil, soybean oil, cottonseed oil, sunflower oil, safflower oil, canola oil, rice oil, peanut oil, flaxseed oil, by being selected from any of coconut oil or palm oil, some have the said biodiesel fuel, by the content of methanol is 0.1% or less, or the generator, a gas engine generator Being a machine can be achieved more effectively.

In the present invention, as a detergent for removing tar, not an aromatic or aliphatic hydrocarbon-based organic solvent-based detergent, but a plant-derived oil such as rapeseed oil, sesame oil, sunflower oil, coconut oil, or palm oil is used. Therefore, the dry distillation gas becomes cleaner. Specifically, when the biomass dry distillation gas was washed by the method according to the present invention, the tar content became 1/100 or less.

It is a schematic diagram showing an example of a power generation system of biomass dry distillation gas according to the related art or the present invention. It is a flowchart which shows the tar removal method which concerns on the power generation system of the biomass carbonization gas which concerns on this invention.

The present invention will be described in detail with reference to the drawings.

Here, the term "tar" used in the present application is a general term for dry distillation liquid obtained from coal, peat or wood, as well as benzene, toluene, phenol or its derivatives (aldehyde, hydroxy compound, thiol, halogenated compound, etc.), biphenyl. Or derivatives thereof (aldehydes, hydroxy compounds, thiols, halogen compounds, etc.), naphthalene or derivatives thereof (aldehydes, hydroxy compounds, thiols, halogen compounds etc.), anthracene or derivatives thereof (aldehydes, hydroxy compounds, thiols, halogen compounds) Etc.) or aromatic hydrocarbons such as pyrene or its derivatives (aldehydes, hydroxy compounds, thiols, halogen compounds, etc.), or furan or its derivatives (aldehydes) , Hydroxy compounds, thiols, halogen compounds, etc., pyrrole or its derivatives (aldehyde, hydroxy compounds, thiols, halogen compounds, etc.), or thiophene or its derivatives (aldehyde, hydroxy compounds, thiols, halogen compounds, etc.) It is a general term for cyclic aromatic compounds, or paraffinic hydrocarbons or their derivatives (aldehydes, alcohols, diols, thiols, halogenated compounds, etc.).

The term "biomass raw material" as used in the present application means waste materials such as forest residues, construction waste materials, livestock excrement, food waste, waste paper, pulp mill waste liquid, sewage or night soil sludge, or residual wood or lumber from construction. Systematic biomass, unused biomass such as rice straw, straw or rice husk, sugar resources such as sugarcane and sugar beet, starch resources such as corn and sweet potato, oil and fat resources such as rapeseed and sesame, or resource crops such as poplar. is there. In addition, in this application, embodiment is mainly demonstrated centering on a wood-based biomass raw material.

FIG. 1 is a schematic view showing an example of a biomass carbonization gas power generation system used conventionally or in the present invention. Basically, the power generation system 10 includes a pyrolytic carbonization device 1, a gas cleaning machine 2, a gas blower 3, a gas holder 4, a generator 5 and a cleaning oil tank 6.

The pyrolysis carbonization device 1 plays a role of a pot for separating a biomass raw material into a solid content and a volatile gas (biomass carbonization gas). By treating the biomass raw material with the pyrolytic carbonization device 1, the solid content of the biomass raw material and the biomass carbonization gas are separated. By the way, since the solid content of the biomass raw material is mainly a carbide (for example, charcoal), it can be reused as a fuel for a fuel engine. The carbonization temperature in the pyrolysis carbonization device 1 is preferably about 450 to 550°C. The reason for the temperature range of the carbonization temperature will be described later.

The thermal decomposition carbonization device 1 is preferably a continuous type, and a known device can be used. Further, in the case of using the continuous type, the efficiency is improved by using the superheated steam together. At this time, the conditions of the superheated steam are preferably a temperature of 500 to 700° C. and a pressure of 100 to 300 mmH ₂ O. As a generator (not shown) for generating superheated steam, a known device may be used as long as it is attached to the pyrolytic carbonization device 1 and used.

The gas scrubber 2 is for cleaning the biomass dry distillation gas separated by the pyrolysis carbonization device 1, and also has the purpose of cooling the dry distillation gas. Conventionally, a hydrocarbon solvent is used as a cleaning solvent regardless of whether it is an aliphatic or aromatic gas oil, kerosene, benzene, xylene, or toluene. However, since these solvents themselves contain the tar defined above, the cleaning effect is not improved, which is not preferable. Although details will be described later, in the present application, instead of these solvents (washing oil), rapeseed oil, sesame oil, soybean oil, cottonseed oil, sunflower oil, safflower oil, canola oil, rice oil, peanut oil, linseed oil, coconut oil, palm are used. Vegetable oil such as oil is used as a cleaning oil. Incidentally, the method of introducing the cleaning oil into the gas cleaning machine 2 may be a commercially available (known) one, but as shown in FIG. A system having a system in which the cleaning oil is circulated in the gas cleaning machine 2 is desirable. The circulation pressure at this time is preferably ² to 5 kg/cm ² . The pressure range of this circulation pressure is based on the reason that the cleaning oil and the dry distillation gas are sufficiently cleaned, and the temperature at which the dry distillation gas cleaned by the gas cleaning machine 2 goes from the gas cleaning machine 2 toward the gas blower 3, That is, the outlet temperature is set to 20 to 40°C. Further, the reason for setting the outlet temperature to 20 to 40° C. is that if the outlet temperature is 40° C. or higher, the dry distillation gas cannot be used as a power source of the generator 5 or the power generation efficiency of the generator 5 is reduced. However, even if the outlet temperature is less than 20° C., the power generation efficiency does not increase so much. The size (width and height) of the gas cleaning machine 2 is arbitrary.

The gas scrubber 2 includes a packing such as an irregular packing or a regular packing for contacting gas and liquid. As for the irregular packing and the regular packing, any one of metal, ceramic and plastic can be used. However, in consideration of the pressure loss of the gas scrubber 2, ordered packing is desirable.

The condenser 7 cools the cleaning oil (oil derived from the above-mentioned plant) circulating in the gas cleaning machine 2 and/or cools the tar component of the biomass carbonization gas which cannot be trapped by the cleaning oil. It is installed for concentration. Further, a cooling tower 8 for cooling the condenser 7 is arranged so that cooling water can be circulated between the condenser 7 and the condenser 7.

Furthermore, the gas cleaning machine 2 may be provided with, for example, a cleaning oil storage tank (not shown). This cleaning oil storage tank is for collecting the oil containing the trapped tar content. The cleaning oil storage tank can be installed by any installation method as long as it is adjacent to the gas cleaning machine 2. The cleaning oil collected in the cleaning oil storage tank can be recycled, for example, as a fuel source for the pyrolysis carbonization device 1.

Incidentally, the connection pipe between the pyrolysis carbonization device 1 and the gas scrubber 2 may be any known and well-known pipe method (for example, pipe pipe), but when the biomass carbonization gas is introduced into the gas scrubber 2. A cooler may be installed in the middle of the piping in order to control the temperature of 1, that is, the inlet temperature to 400° C. or lower. However, the system and method according to the present invention are sufficiently established without installing the cooler. Further, in the connection between the pyrolytic carbonization device 1 and the gas cleaning machine 2, it is possible to install a temperature sensor for measuring the inlet temperature of the gas cleaning machine 2 in the middle of the pipe.

Similarly, the connection pipe between the gas cleaning machine 2 and the gas blower 3 may be any known and well-known piping method (for example, pipe piping), but in the middle of the connection pipe or the gas discharge port for dry distillation gas of the gas cleaning machine 2. That is, an optional and known temperature sensor may be installed to measure the outlet temperature.

Next, as the gas blower 3 and the gas holder 4, known ones may be used. Further, as the generator 5, a known one such as a gas turbine type generator or a gas engine type generator can be used. The gas blower 3, the gas holder 4, and the generator 5 may be connected by any known and well-known piping method (for example, pipe piping). Further, the generator 5 can be used not only for the purpose of power generation but also for the boiler of a greenhouse or the like by utilizing the exhaust heat of the generator.

Next, a tar removal method relating to the biomass carbonization gas power generation system according to the present invention will be described with reference to the flowchart of FIG. It should be noted that description will be given using FIG. 1 and the reference numerals shown in FIG. 1 as necessary.

First, the biomass material is pyrolyzed (step S1). For example, in order to pyrolyze this biomass raw material, it is pyrolyzed by the pyrolytic carbonization apparatus 1 shown in FIG. As for the pyrolytic carbonization apparatus 1, a known type may be used regardless of whether it is a continuous type or a batch type, as described above. At this time, the carbonization temperature (thermal decomposition temperature) is preferably about 450 to 550°C. If the carbonization temperature is lower than 450°C, carbonization does not occur, and if it is 550°C or higher, the biomass raw material may ignite. The desired outlet temperature here will be described in the next cleaning and cooling step. In addition, as for the pyrolysis (carbonization) time of the biomass raw material in step S1, it is desirable that 10 to 20 kg of a sample (for example, wood chips) be treated per hour. If the sample is 20 kg or more, the carbonization is not sufficiently performed, and if it is less than 10 kg, the carbonization is accelerated at once, and sufficient biomass dry distillation gas to be used as a power source for the generator 5 or the like is generated. I can't get it.

Further, in step S1, the efficiency is increased by using the superheated steam together. The conditions of the superheated steam at this time are desirably a temperature of 500 to 700° C. and a pressure of 100 to 300 mmH ₂ O. The reason for adopting this condition is based on the range of the carbonization temperature.

Further, the temperature of the dry distillation gas (biomass dry distillation gas) separated from the biomass raw material in step S1 is preferably 400° C. or lower before entering the next cleaning step, that is, the inlet temperature.

Next, the biomass dry distillation gas separated in step S1 is washed and cooled (washing and cooling step: step S2). In step S2, as described above, vegetable oils such as rapeseed oil, sesame oil, soybean oil, cottonseed oil, sunflower oil, safflower oil, canola oil, rice oil, peanut oil, linseed oil, coconut oil, and palm oil are used as cleaning oils. Alternatively, biodiesel fuel can also be used as a cleaning oil. By the way, this cleaning oil is circulated in the known gas cleaning machine 2 shown in FIG. 1, and the circulation pressure at that time is preferably ² to 5 kg/cm ² . As described above, when the circulation pressure is 2 kg/cm ² or less, the cleaning oil and the dry distillation gas are cooled, but the dry distillation gas is not sufficiently cleaned and removed, and the circulation is continued. If the pressure is higher than 5 kg/cm ² , the dry distillation gas and the cleaning oil are sufficiently cooled, but the dry distillation gas and the cleaning oil are not sufficiently cooled.

When using vegetable oil as the cleaning oil, it is not necessary to consider the minor components contained in the vegetable oil, but when using biodiesel fuel as the cleaning oil, methanol is used against the biodiesel fuel. Content of 0.1% or less is desirable. Generally, biodiesel fuel is a fuel derived from fatty acid methyl ester obtained by methyl esterifying the vegetable oil (food oil) and methanol mentioned above and removing glycerin as a by-product. However, since the esterification reaction is generally a reversible reaction, methanol remains if the purification is insufficient. Here, when biodiesel fuel is used as the cleaning oil, if the content of methanol is 0.1% or less, the methanol itself is counted as the tar content, but other tar content and the power generation efficiency of the generator are It is not much different from when it was washed with other vegetable oils. On the other hand, when the methanol content is more than 0.1%, not only the tar content is counted, but also the power generation efficiency of the generator is lowered, and the generator is broken.

Here, the desired outlet temperature (20 to 40° C.) refers to the temperature of the biomass dry distillation gas at the time of moving from the gas cleaning machine 2 to the gas blower 3 shown in FIG. 1, that is, the temperature of the washed biomass dry distillation gas. When the outlet temperature is 40° C. or higher, the dry distillation gas cannot be used as the power source of the generator 5 or the power generation efficiency is reduced, and even if the outlet temperature is less than 20° C., the power generation efficiency is not so much improved.

The tar content of the biomass dry distillation gas cleaned and cooled in step S2 is removed to 1/100 or less before the cleaning. The components of the biomass dry distillation gas that have been washed and cooled in step S2 are carbon dioxide gas, carbon monoxide, hydrogen, methane, and water.

Next, the washed biomass dry distillation gas is stored in the gas holder 4 through the gas blower 3 (step S3). The flow rate of the biomass carbonization gas in step S3 is not particularly limited.

Next, the biomass dry distillation gas stored in the gas holder 4 is used as a power source such as a generator (step S4). The generator mentioned here is assumed to be a generator used in a power generation system using biomass carbonization gas (see FIG. 1), and is a gas turbine or gas engine type generator as described above.

Although the embodiment of the tar removal method according to the power generation system for biomass carbonization gas according to the present invention has been described above, the present invention is not limited to the above embodiment, and the present specification, the drawings, and/or the claims. It goes without saying that various embodiments can be adopted without departing from the matters described in (1).

Examples of the above embodiment will be further described. It should be noted that the examples described in the present specification are merely examples, and like the above-described embodiments, various examples are possible without departing from the matters described in the present specification, the drawings, and/or the claims. take.

In addition, this embodiment will be described with reference to the schematic diagram of the biomass dry distillation gas power generation system shown in FIG. 1 as necessary.

First, in the present example, the pyrolysis carbonization apparatus 1 of FIG. 1 was a continuous carbonization apparatus combined with superheated steam, and the samples were wood chips. Then, the wood chips are heat-treated (carbonized) at 16 kg/hour (h) in the apparatus, the heating temperature is 500° C., the temperature and pressure of superheated steam are 600° C. and 250 mmH ₂ O, respectively, to generate biomass carbonization gas. It was The biomass dry distillation gas generated at this time was 10 nm ³ /h and the generation temperature was 300° C., and the tar content contained in the dry distillation gas at the time of biomass dry distillation gas generation was 120 mg/nm ³ per 1 nm ³ of the dry distillation gas. (This is referred to as "before washing" shown in Table 2 described later). The components of the biomass carbonization gas are shown in Table 1 below.

次に、発生させたバイオマス乾留ガスを、図１のガス洗浄機２に通し、洗浄油を菜種油として洗浄した。なお、この洗浄油としての菜種油については、循環圧力を３ｋｇ／ｃｍ^２として、ガス洗浄機２内を循環させ、洗浄をして、当該乾留ガスの温度を３０℃まで冷却した。この乾留ガスの成分及び乾留ガスに含まれるタール分をレーザガス分析計で測定したところ、この洗浄後でも乾留ガスの成分は表１と変わらず、タール分が乾留ガス１ｎｍ^３当たり１ｍｇ／ｎｍ^３に減少した（これを後述する表２で表す「洗浄後」とする）。ガス洗浄前後のタール分の量を次の表２に示す。

Next, the generated biomass dry distillation gas was passed through the gas washing machine 2 of FIG. 1 to wash the washing oil as rapeseed oil. The rapeseed oil as the cleaning oil was circulated in the gas cleaning machine 2 at a circulation pressure of 3 kg/cm ² for cleaning, and the temperature of the dry distillation gas was cooled to 30°C. The tar present in component and carbonization gas in the carbonization gas was measured with a laser gas analyzer, components of carbonization gas even after the washing is not changed as in Table 1, tar is a carbonization gas 1 nm ³ per 1 mg / nm ³ Decreased (this is referred to as “after washing” shown in Table 2 below). The amount of tar content before and after gas cleaning is shown in Table 2 below.

表２において、本発明のタール除去方法を用いた場合、ガスの性状（成分）を変えずに、タール分のみを洗浄前から１００分の１以下に減らすことが可能であるということが実証できた。

In Table 2, it can be demonstrated that when the tar removal method of the present invention is used, it is possible to reduce only the tar content to 1/100 or less from before cleaning without changing the properties (components) of the gas. It was

Next, when the biomass dry distillation gas after washing was used as a power source of a gas engine type generator (corresponding to the generator 5 in FIG. 1), 5 kW of power was generated.

The tar removal method according to the power generation system of biomass carbonization gas according to the present invention uses plant-derived oil such as rapeseed oil, sesame oil, sunflower oil, coconut oil, palm oil, etc., so that carbonization gas becomes cleaner, In addition to being used as the power source of the generator of the power generation system according to the present invention, it can be applied to devices and systems that require gas cleaning.

1 Pyrolysis Carbonization Device 2 Gas Cleaning Machine 3 Gas Blower 4 Gas Holder 5 Generator 6 Cleaning Oil Tank 6a Circulation Pump 7 Condenser 8 Cooling Tower 10 Biomass Carbon Distillation Gas Power Generation System

Claims (4)

A pyrolysis step of pyrolyzing and carbonizing a biomass material,
A washing/cooling step of washing and cooling the biomass carbonization gas separated in the thermal decomposition step,
A step of storing the biomass dry distillation gas washed in the cleaning/cooling step, and a step of using the biomass dry distillation gas as a power source of a generator,
In the pyrolysis step, the biomass raw material is pyrolyzed at 10 to 20 kg per hour, and the carbonization temperature is 450 to 550° C., and in the pyrolysis step, superheated steam is further used in combination, and The superheated steam has a temperature of 500 to 700° C., a pressure of 100 to 300 mmH ₂ O, and in the washing/cooling step, the biomass carbonization gas is washed with vegetable oil or biodiesel fuel, and 20 to A method for removing tar from a biomass carbonization gas power generation system , wherein the vegetable oil is cooled to 40° C., and the vegetable oil is circulated at a circulation pressure of 2 to 5 kg/cm ² for use . The biomass according to claim 1, wherein the vegetable oil is selected from rapeseed oil, sesame oil, soybean oil, cottonseed oil, sunflower oil, safflower oil, canola oil, rice oil, peanut oil, linseed oil, coconut oil or palm oil. A method for removing tar in a dry distillation gas power generation system. The method for removing tar from a biomass carbonization gas power generation system according to claim 1, wherein the biodiesel fuel has a methanol content of 0.1% or less. The tar removal method according to any one of claims 1 to 3 , wherein the power generator is a gas engine type power generator.

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