JP4589226B2 - Method for producing fuel carbide and fuel gas - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a fuel carbide and a fuel gas production method in which a biomass raw material is charged into a shaft furnace and is subjected to dry distillation gas by partial combustion heat of the biomass raw material to generate carbide and dry distillation gas.

  An external heat kiln method and a partial combustion fluidized bed method have been developed as a dry distillation furnace for converting a biomass raw material such as woody biomass and biomass materials such as organic waste into dry distillation gas. When biomass raw material is gasified by dry distillation in an externally heated kiln or a partially combusted fluidized bed, it is difficult to gasify the inside of the kiln unless the raw material is crushed and made fine, and the fluidized bed cannot flow. In addition, pretreatment for crushing the biomass raw material to about 20 mm or less is essential, and extra crushing power for that is required.

  In addition, when the biomass raw material is building waste, metal (bolts, nails), etc. are mixed in, and metal separation is required in advance to protect the crusher, and a separation device for these metals was necessary. . However, the metal is present in a mixed state with the biomass and is difficult to recover. Even if the metal can be recovered, it is not distributed as a valuable resource as it is, and manual sorting or the like is necessary later.

  On the other hand, various methods for generating power from biomass have been developed. However, none of these methods could be realized due to the complexity of the treatment process, the size of equipment costs, and the limit on the amount of biomass that can be collected.

Therefore, it has been proposed to partially oxidize carbonaceous resources with oxygen and water vapor in a shaft furnace as a process that is economical and simple even when a small amount of biomass is established in the process of carbonization of biomass raw material (patent) Reference 1). By using the shaft furnace, it is possible to minimize troublesome pretreatment that requires wasteful crushing power as compared with the external heat kiln method and the partial combustion fluidized bed method. Furthermore, by providing a reforming furnace in the downstream, different energy conversion methods are provided according to the properties of various carbonaceous resources, enabling the conversion of highly efficient carbonaceous resources to gas energy.
JP 2004-41848 A

  In the shaft furnace, partial oxidation is performed in the shaft furnace, but the temperature of the partial combustion region changes according to the quality of the biomass raw material (calories, moisture content). According to the experiment, in the case where the water content of the biomass raw material is reduced, a local high temperature region of 1200 ° C. or higher is generated in the partial combustion part, and the ash content in the raw material is melted by the local high temperature contributing to the partial oxidation in the shaft furnace. Growing up and producing clinker.

In addition, the endothermic reaction of the solution reaction (CO ₂ + C → 2CO-Q) and the water gas reaction (H ₂ O + C → CO + H ₂ -Q) proceeds in the high temperature region, and the temperature of the generated gas rapidly decreases. As a result, the temperature of the generated gas cannot be stably maintained at a temperature (300 ° C. or higher) at which tar does not adhere to the gas pipe, and tar adheres to the gas pipe and grows.

  In the case where the moisture content of the raw material increased, local high temperatures did not occur in the partial combustion section, but the inside of the furnace was too cold and the carbonization reaction was insufficient, resulting in a large amount of uncarburized material.

  Accordingly, the present invention provides a fuel carbide and a fuel capable of stably producing fuel carbide and fuel gas by preventing generation of clinker and adhesion of tar in the production of fuel carbide and fuel gas by a shaft furnace. A method for producing a gas is provided.

The present invention provides a carbonized fuel for fuel and a method for producing fuel gas in which carbonized gas and carbonized gas are generated by using the partial combustion heat of biomass raw material as a heat source in a shaft furnace, and in the method for producing fuel gas and air, steam as oxidants for partial combustion By using a mixture and changing the oxidant oxygen concentration and the amount of steam by changing the amount of steam added to the air based on the deviation of the temperature of the gas generated in the shaft furnace from the set value of the generated gas temperature. , and controlling the temperature of the generated gas to a predetermined range.

  Combustion with the air-fuel ratio controlled externally and supplying hot gas to the shaft furnace with zero oxygen can reliably prevent the generation of clinker due to partial oxidation. Further, the temperature of the generated gas can be controlled by controlling the temperature of the hot gas. In that case, in the case of external combustion, there is no concern about clinker generation and tar adhesion, and the range of biomass raw materials that can be handled is larger.

  The present invention does not generate clinker in the furnace by changing the ratio of the mixture of oxygen and steam according to the temperature of the gas generated in the shaft furnace, or by changing the temperature of the hot gas, and By maintaining the temperature of the generated gas in a temperature range where tar adhesion does not grow, the fuel carbide and fuel gas can be produced stably.

  Further, according to the present invention, it is possible to carbonize the furnace contents over a long period of time by providing the hot gas supply unit in two upper and lower stages, and it is possible to prevent the occurrence of uncarburized materials. The height can be greatly reduced and the size can be reduced.

  In addition, the present invention provides a cooling device that is required to safely carry the carbide through air flow and remove metal by providing a steam blowing nozzle that blows steam for cooling the carbide that has been heated in the furnace. It becomes possible to make it compact and cheap.

  Moreover, the present invention can remove the shelves by providing an inert gas blowing nozzle that periodically blows an inert gas rapidly into the shaft portion.

  In addition, since the present invention can use fuel carbide and fuel gas as fuel for thermal power generation facilities, it can generate power by converting coal for power generation into biomass, and the fuel gas is tar. Since it can be controlled to a temperature at which it does not adhere, it can be directly connected to a pulverized coal boiler and can be burned as it is, so there is no need to provide an expensive gas refining and tar removal device.

  FIG. 1 is a sectional view showing a shaft furnace for carrying out the method of the present invention.

  In order to charge biomass raw material to the top of the shaft furnace 1, a charging device 2 that is double-sealed by an upper gas seal valve 2a and a lower gas seal valve 2b is provided. A shaft portion 3 for carbonizing the charged biomass material is disposed at the lower portion of the charging device 2. A pusher 5 for pushing carbonized carbide to the carbide discharge chute 4 is provided at the lower portion of the shaft portion 3. The shaft portion 3 is provided with a gas supply portion 6 for supplying a gas generated from a mixture of air and steam as an oxidizing agent for partial combustion in the shaft portion. Furthermore, a temperature detector 10 for measuring the temperature of the generated gas is arranged above the stock level 9 of the shaft portion 3.

  The biomass raw material charged in the shaft furnace 1 is dry-distilled by a heat source partially burned by the oxidant supplied from the gas supply unit 6 in the shaft unit 3 to generate carbide and fuel gas. The carbide is generated by the pusher 5. The fuel gas is pushed out to the carbide discharge chute 4 and exhausted from the gas pipe 11.

  Carbonaceous resources such as woody waste such as waste wood, dry sludge, waste plastic material, building waste material, RDF, and general waste can be used as biomass raw materials. The biomass raw material can be put into a shaft furnace as it is by roughly crushing it to 100 mm to 200 mm, and the conventional crushing to about 20 mm and metal separation are not necessary, and power and equipment costs can be saved. . Also, because the crushing dimensions are large, when a part of the discharge part is reached in an uncarburized state, shelves have been generated at the throttle part around the discharge device. It can be discharged as it is. Furthermore, carbide and metal are easily separated because they are heated in the furnace, and can be separated into carbide, uncarburized, and metal that can be provided directly to a pulverized coal boiler by specific gravity separation. Further, the uncarburized material after the metal recovery can be reintroduced into the shaft furnace together with the raw material, and is directly reduced and carbonized in a high temperature atmosphere in the shaft furnace, and finally converted into carbide and gas.

  According to the detection signal output from the temperature detector 10, the mixing ratio of air and steam is adjusted according to the temperature of the generated gas. By changing the ratio of steam mixed with air according to the temperature of the generated gas, the temperature of the partial combustion region can be controlled to a temperature level at which solution reaction and water gas reaction do not proceed rapidly, and the generated gas temperature Can also be controlled. As a result, even if the quality of raw materials such as biomass raw materials and organic wastes with various compositions and moisture content changes, local high temperature does not occur in the shaft furnace, and clinker is generated in the furnace. In addition, the temperature of the generated gas can be controlled to 300 ° C. or higher at which tar adhesion does not grow.

  The gas supply unit 6 for supplying a gas generated from a mixture of air and steam as an oxidant for partial combustion into the shaft part is a state in which fuel such as LNG and heavy oil for initial temperature increase, air and steam are mixed in advance It is best to supply with. Furthermore, in order to prevent oxygen leakage to the generated gas, a small amount of LNG or the like may be added to reliably maintain the fire point near the oxidant introduction portion.

  The oxygen concentration of the oxidant supplied from the gas supply unit 6 is controlled to 10 to 18 vol% on a wet basis. If the oxygen concentration in the oxidant is 10 vol% or less, the raw material does not undergo an oxidation reaction, and oxygen may escape into the generated gas, which is dangerous. On the other hand, when the oxygen concentration is 18 vol% or more, the partial combustion temperature rises too much and clinker is easily generated.

  The gas supply unit 6 is provided in two upper and lower stages. When the gas supply unit 6 has a single stage, the temperature history varies extremely depending on the distance from the gas supply unit 6 in the shaft portion, and when the gas supply unit 6 is far away, the gas supply unit 6 may be discharged in an uncarbonized state. However, when the gas supply unit 6 has two stages, the volume is reduced by the first stage gas supply unit 6a, and the descent speed in the furnace decreases. Here, by providing the second-stage gas supply unit 6b in the lower part, it becomes possible to carbonize the furnace contents over a long period of time, and the generation of uncarburized can be prevented.

  FIG. 2 is a graph showing the relationship between the generated gas temperature and the blowing of steam when the gas supply units 6 are provided in two upper and lower stages and processed at 20 T / day as a biomass raw material.

At this time, the target raw material was operated for general waste (moisture 45%). Therefore, at time A, the raw material was changed to dry waste (water content 10%). Then, the temperature of the generated gas began to decrease. Furthermore, according to the composition continuous analysis of the generated gas, an increase in CO and H ₂ was observed. That is, it is possible to confirm an increase in CO and H ₂ due to the solution reaction and the water gasification reaction and a decrease in the generated gas temperature.

Control was automatically entered at time B. Thereafter, based on the deviation from the set value of the generated temperature (400 ° C.), the amount of steam added automatically increased and decreased, and the generated gas temperature was basically controlled to 400 ° C. That is, from time B, an increase in the amount of steam (= a decrease in the concentration of the oxidizing material O ₂ ) lowers the temperature level around the gas supply unit, resulting in a temperature level at which solution reaction and water gas reaction do not occur, and endothermic reaction occurs. As a result, the generated gas temperature could be maintained at a temperature at which tar was not generated. Table 1 shows the relationship between the amount of material drop and gas temperature at the first and second stages.

  Further, from Table 1, when the superficial velocity at the top of the furnace is designed based on 1 Bm / s, the descending speed of the raw material at the upper part of the first stage gas supply unit 6a is rapidly 6.2 m / h. It is descending. Therefore, in the conventional shaft furnace, in order to ensure the residence time of the raw material in the furnace for about 2 h, it is necessary to secure a height of about 13 m. In the present invention, by gasifying the gas supply unit 6 in two stages, the gasification component (moisture, volatile content) of the raw material is reduced by about 70% in the lower part of the first stage gas supply unit 6a. Furthermore, the bulk specific gravity also changes from 0.15 to 0.2, and the descent speed is 1.4 m / h. Therefore, if the residence time of the upper part of the second stage gas supply unit 6b is secured about 2 m, the residence time of about 1.5 hours can be secured, and the height of the upper part of the first stage gas supply unit 6a is the lowest. It is sufficient to secure about 3 m (about 30 min) in consideration of the fluctuation allowance of the limited batch charging, and as a result, the shaft portion 3 can be greatly downsized (13 m → 5 m). Further, it can be sufficiently secured in the high temperature region at the upper part of the second stage hot gas supply unit 2, and the generation of uncarburized materials can also be suppressed.

  A steam blowing nozzle 7 for blowing steam for cooling carbide that has been heated in the furnace is provided at the bottom of the shaft portion 3. By providing a nozzle 7 for blowing steam further from the lowermost gas supply unit 6b and supplying steam from there, the temperature of the carbide can be cooled from the 800 ° C. level to 100 to 200 ° C. As a result, it becomes possible to make the cooling device required for safely carrying the air current and removing the metal more compact and cheaper. Further, when the cooling device is simply provided directly, it becomes possible to recover the sensible heat of the carbide that has been wasted into the process with steam, and as a result, the process thermal efficiency is improved.

  The shaft portion 3 may be provided with an inert gas blowing nozzle 8 for rapidly blowing an inert gas periodically in order to remove the shelves. Periodically, an inert gas is rapidly blown from the nozzle 8 to remove the carbide shelves. In the shaft furnace, it is known that a shelf suspension phenomenon occurs on the wall surface depending on the shape of the contents. This shelving phenomenon occurs when the weight of the contents is held by the frictional resistance of the wall surface. Therefore, in order to reduce the frictional resistance of the wall surface, the inert gas is periodically ejected from a large number of nozzles 8 provided around the wall surface, thereby eliminating the wall adhesion force = frictional resistance and eliminating the generated shelf suspension. can do. Furthermore, the occurrence of shelves can be prevented by ejecting regularly. Each nozzle 8 is effective when it has an inert gas filling tank and a switching valve. However, a simple tube may be provided and ejected all at once. Further, it is effective that the nozzles 8 are provided around the periphery at a pitch of at least 200 mm.

  FIG. 3 is a sectional view showing another embodiment of the gas supply unit 6. A combustion chamber 12 having a throttle portion 12a formed inside the furnace is provided outside the shaft portion 3, and a combustion burner 13 is combusted in the combustion chamber 12 to generate a hot gas without oxygen, and the hot gas is supplied from the throttle portion 12a into the furnace. Into the heat source of partial combustion heat. If it is used as fuel, it is sufficient to use heavy oil LPG or the like, but it is more preferable to recycle dry-distilled fuel gas.

  By changing the ratio of air, oxygen and fuel gas to each other, the temperature of the hot gas can be changed. When the temperature of the gas generated from the upper part of the shaft furnace decreases, the endothermic reaction called solution reaction or water gas reaction can be suppressed by lowering the temperature of the hot gas, and the furnace top temperature can be maintained. . In order to suppress the generation of soot, it is effective to add a certain amount of steam.

  FIG. 4 is a diagram showing a system that uses carbide for fuel and fuel gas as fuel for coal-fired thermal power generation facilities.

  The fuel gas produced in the shaft furnace 1 is burned by a casburner 14 installed in a coal-fired thermal power generation facility 13, and the obtained carbide is mixed in a coal mill 15 for thermal power generation and burned by a pulverized coal burner 16. By replacing the coal for power generation with biomass, power is generated. By using an existing pulverized coal boiler or the like, the generated gas can be burned as it is without containing expensive gas refining and tar removal equipment. It can be used and burned as it is.

It is sectional drawing which shows the shaft furnace for enforcing the method of this invention. It is a graph showing the O ₂ concentration of the relationship between evolved gas temperature and oxidizer. It is sectional drawing which shows another Example of a hot gas supply part. It is a figure which shows the system which utilizes the carbide | carbonized_material and fuel gas for fuel as a fuel of a coal burning thermal power generation installation.

Explanation of symbols

1: Shaft furnace 2: Charging device 2a: Upper gas seal valve 2b: Lower gas seal valve 3: Shaft part 4: Carbide discharge chute 5: Pusher 6: Gas supply part 6a: First stage hot gas supply part 6b: Second stage hot gas supply unit 7: Steam blowing nozzle 8: Inert gas blowing nozzle 9: Stock level 10: Temperature detector 11: Gas pipe 12: Combustion chamber 12a: Throttle unit 13: Coal-fired thermal power generation facility 14: Gas burner 15: Coal mill 16: Pulverized coal burner

Claims (7)

In the method for producing fuel carbonized fuel and fuel gas in which carbonized gas and carbonized gas are generated by dry distillation gas using the partial combustion heat of biomass raw material as a heat source in the shaft furnace,
By using a mixture of air and steam as the oxidant for partial combustion, and changing the amount of steam added to the air based on the deviation of the temperature of the gas generated in the shaft furnace from the set temperature of the generated gas A fuel carbide and a method for producing fuel gas, wherein the temperature of the generated gas is controlled within a certain range by changing the oxidant oxygen concentration and the amount of steam.   The method for producing carbide and fuel gas according to claim 1, wherein the oxygen concentration of the oxidant is controlled to 10 to 18 vol% on a moisture basis. 3. The method for producing fuel carbide and fuel gas according to claim 1 , wherein the maximum size of the biomass raw material is 100 mm to 200 mm . The method for producing a carbide for fuel and a fuel gas according to any one of claims 1 to 3, wherein the hot gas supply section of the shaft furnace has two upper and lower stages . The method for producing carbide and fuel gas according to any one of claims 1 to 4, wherein the carbide heated to a high temperature in the furnace is cooled by blowing steam from a nozzle located at the bottom of the furnace . The method for producing fuel carbide and fuel gas according to any one of claims 1 to 5, wherein the inert gas is rapidly blown in periodically to remove carbide shelves . The fuel gas is a combustion gas for a gas burner installed in a coal-fired thermal power generation facility, and the obtained fuel carbide is a fuel that is mixed with a coal mill for thermal power generation and burned with a pulverized coal burner. The method for producing carbide and fuel gas according to any one of claims 1 to 6.

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