JP3979721B2 - Simple continuous activated carbon production equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the vertical downflow reactor, various biomass containing building waste wood is introduced from the top of the reactor to form a downward moving bed of biomass in the reactor, while hot gas is supplied. An internal heating system that continuously supplies activated carbon by supplying from the top of the furnace, from drying of biomass to generation of activated carbon (thermal energy of volatiles of biomass and heat of combustible gas generated by water gasification reaction) Uses energy) to provide continuous activated carbon production equipment.
Note) Downward moving floor The grate is fixed to the lower part of the furnace, and the raw material is supplied from the upper part of the furnace. Since the activated carbon generated in the furnace is taken out from below, the constituent materials of the floor move downward. Therefore, it is called a downward moving floor.
[0002]
[Prior art]
FIG. 1 shows a conventional process for producing powdered activated carbon from biomass. Conventionally, a process for producing charcoal by drying / dry distillation of biomass and a process for producing activated carbon by activating charcoal with gas (water vapor or carbon dioxide) are usually independent of each other. FIG. 2 shows a process for producing charcoal by drying biomass by a rotary dryer and then dry-distilling by external heating in a separate carbonization cylinder. FIG. 3 shows a process for producing activated carbon by activating charcoal with water vapor. FIG. 4 shows an example of producing activated carbon consistently from biomass in a rotary kiln. In this case, the heated gas is obtained by burning heavy oil or gas in the combustion furnace 2. In the former, the apparatus is complicated, and in the latter, the apparatus is excessive. Therefore, both the construction cost and operation cost of the apparatus are high, and the apparatus cost of the activated carbon is high.
[0003]
[Problems to be solved by the invention]
1. The present invention forms a moving bed using biomass as a raw material in a gasification reaction furnace, and flows a high-temperature gas for heating and reacting the biomass from above with air, so that stable carbonization / activation reaction can be performed across the furnace. The purpose is to provide a low-cost activated carbon production device that can be generated uniformly over the surface and can continuously perform a consistent process from biomass to activated carbon in a structurally simple and compact reactor. .
[0004]
2. When biomass such as building waste wood containing chemical substances is used as a raw material, the gas at the outlet of the reactor containing the combustible gas (H ₂ , CO, CnHm, etc.) generated by the carbonization / activation reaction is burned at a high temperature of 1000 ° C or higher. After oxidizing and decomposing harmful substances in the gas to make them harmless, a part of the high-temperature gas is recycled to the top of the gasification reactor and used for the reaction, and the remaining high-temperature gas is used for high-temperature and high-pressure steam. It aims at providing the boiler which generates.
[0005]
[Means for solving the problems]
(1) In order to solve the above-mentioned problems relating to the production of activated carbon, the present inventors installed a grate or an equivalent activated carbon / combustible gas discharge device in the lower part of an upright vertical reactor and installed it from the upper part of the reactor. Biomass is charged, and a moving bed of biomass is formed on the upper part of the grate and the equivalent device. On the other hand, high-temperature gas containing several to dozens of acid cords is introduced from the upper part of the furnace, and the moving bed is moved upward. When flowing from the bottom to the top, the hot gas reacts with the biomass to form reaction layers of drying, volatilization, combustion, carbonization, and activation in order from the top. Water vapor obtained by moisture evaporation and volatile combustion is mixed with high-temperature gas and activates carbides. The hot gas descending in the moving bed flows evenly across the entire cross section of each reaction layer by spreading to the side by suppressing the resistance of the moving bed to gas flow and the reaction product gas being suppressed by the descending hot gas. Paying attention to this, when biomass, high-temperature gas and air are introduced from the top in an experimental furnace as shown in FIG. 5-c, the reaction in each layer is uniformly performed, and the activated carbon can be taken out from the grate and the equivalent device part It was confirmed that the present invention was reached. There are the following four methods for generating and supplying the hot gas.
[0006]
1. Supplying auxiliary fuel and air to the top of the reactor, and generating and supplying a high-temperature gas containing oxygen at a concentration of several to tens of percent by a combustion reaction at the top of the reactor (FIG. 5-a)
[0007]
2) Use auxiliary fuel only at the time of reactor start-up in items 1 and 2. When the reaction in the furnace stabilizes and the moving bed begins to form, the auxiliary fuel is gradually reduced, and the volatile content of biomass is used as an alternative to auxiliary fuel. How to use (Figure 5-a)
[0008]
3. When the reaction in the furnace becomes stable in the item 1 and 1, a part of the combustible gas extracted from the lower part of the reaction furnace is recirculated and used instead of the auxiliary fuel (FIG. 5-b).
[0009]
4. A method of burning a combustible gas extracted from the lower part of the furnace at a high temperature of 1000 ° C. or more and supplying a part of the combustion gas together with air to the top of the furnace as shown in FIG.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
The simplified continuous activated carbon production apparatus of the present invention will be described with reference to FIG. The basics of the activated carbon generation reaction are the same in FIGS.
[0011]
1) Biomass (waste wood, etc.) crushed to several mm to several hundred mm from a biomass charging port 2 provided at the top of the reaction furnace 1 is continuously charged into the furnace so as to be uniform across the furnace cross section. .
[0012]
2) The biomass charged into the furnace is in the order from the top above the grate 3 provided in the lower part of the reactor 1 in the order of dry layer a, volatile layer b, combustion layer c, carbonized layer d, activated layer e and activated carbon layer. A moving bed composed of (i) is continuously formed. (The mechanism for forming layers A to F will be described later.)
[0013]
3) Similarly, a high temperature gas containing several percent to several tens of percent oxygen is blown into the upper portion of the furnace from a gas blowing port 4 provided at the top of the reaction furnace 1.
[0014]
4) The hot gas flows down from the top through the moving bed. At that time, the biomass in the dry layer (i) at the top of the moving bed is heated and dried with a high-temperature gas, slowly settles, and moves to the volatile layer port. The high-temperature gas, which has received part of the heat retained by drying, flows down into the volatile layer while containing the moisture of the biomass in the form of water vapor. At that time, the volatile matter jumps out of the biomass into the hot gas. Volatile components are oxidized and burned by oxygen in the high temperature gas while flowing down with the high temperature gas to form a combustion layer c. In the lower part, a part of the solid content is burned to form a carbonized layer d. Thermal energy and water vapor generated by combustion of the volatile fuel and part of the solid are used for the following gasification reaction.
[0015]
5) In the carbonized layer D, part of the carbide generated by combustion and carbon dioxide in the high-temperature gas absorb heat energy as shown in the following formula (1) to generate carbon monoxide (combustible gas).
C (Carbide) + CO ₂ = 2CO−38, 200 kcal / kmol (1)
[0016]
6) In the lower part of the carbonized layer 2, the water vapor generated by the drying and volatile matter combustion is a large number of fine pores of the carbide (the biomass releases the volatile matter from the inside, and a part of the organic matter burns) Then, carbon dioxide (CO ₂ , CO, etc.) is infiltrated into the pores that are released to the outside, and the water gasification reaction of the following formulas (2) and (3) is caused to occur. The pores are further expanded and developed to activate the carbide.
_{C + H 2 O = CO +} H 2 -28,200 (2)
C + 2H ₂ O═CO ₂ + 2H ₂ −18,200 (3)
Even in the activation of the carbide, thermal energy is absorbed as shown in the equations (2) and (3). In ordinary biomass, the amount of water vapor required for the reactions of the above formulas (2) and (3) is sufficient when the amount of water vapor obtained by drying of biomass and volatile matter of biomass is sufficient, but the activation of carbides is strengthened. For example, steam is added from the auxiliary nozzle 5. In this activation layer E, the carbide becomes activated carbon. FIG. 6 shows a moving floor model.
[0017]
7) On the grate 3 is formed an activated carbon layer that has sunk from the activation layer, and is continuously taken out from the furnace through the activated carbon outlet 6. On the other hand, the combustible gas generated by the reactions of the above formulas (1), (2), and (3) is sent to the rear combustion furnace 8 through the communication flue 7 together with the remaining gas.
[0018]
8) FIG. 7 shows changes in biomass mass and gas temperature at the height of the reactor obtained as a result of the experiment in the reactor shown in FIG. In the volatilization / combustion zone, the mass rapidly decreases due to the volatile component jumping out, and the gas temperature rapidly increases. In the activation layer, the mass gradually decreases due to the water gasification reaction, and the gas temperature rapidly decreases. When activation is completed and the activated carbon layer is formed, both the mass and the gas temperature become constant. FIG. 8 shows a change in the composition of the hot gas flowing down in the furnace depending on the furnace height. H ₂ and CO are generated in the middle of the volatile layer, the generation increases in the activation layer, and the generation becomes zero in the activated carbon layer. As shown in FIGS. 5 and 6, biomass is introduced from the top of the furnace to form a moving bed above the grate 3 and individual solids settle downward from above, while hot gases (including oxygen) are also present. In the apparatus of the present invention, which is introduced from the top of the furnace and flows down in the moving bed, accumulation of coarse biomass and reaction product solids in the moving bed becomes a resistance to the gas flow and gives a rectifying effect (FIG. 9). -A). As a result, the high temperature gas flows down in a uniform distribution over the entire cross section of the furnace, reacts with biomass and the like, and the product gas is forced to flow downward by being suppressed by the descending high temperature gas. At that time, due to the synthesis of the weak rising vector of the product gas and the strong descending vector of the hot gas, the product gas flows down along with the hot gas while spreading in the lateral direction (see FIG. 9B). Depending on the above two factors (shown in FIGS. 9a and 9b), the reaction is carried out uniformly across the entire furnace cross section (while in the conventional fixed bed reactor, the gas flows upward in the fixed bed. If there is a drift of the hot gas, the gasification reaction of the part where the hot gas is large becomes active, the combustion of the part is activated, the rising power of the hot gas increases, and the hot gas tends to concentrate on the part. And uneven reaction occurs across the furnace cross section). As a result, in the apparatus of the present invention, as shown in FIGS. 7 and 8, the reaction of drying, volatilization, combustion, carbonization, and activation is stably performed in the reaction furnace, and the yield of activated carbon can be increased. In the case of biomass with low volatile content and moisture, or when strengthening the activation of carbides, an auxiliary steam nozzle is a necessary condition, but with other biomass, sufficient steam can be obtained from the biomass in steady operation Therefore, an auxiliary water vapor nozzle is unnecessary.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
1. FIG. 10 shows an embodiment of the present invention.
In this example, activated carbon is produced in a reactor, reducing gas generated at that time is combusted in an adjacent boiler, high-temperature and high-pressure steam is produced by the generated thermal energy, and it is sent to a turbine / generator for electricity. to make. On the other hand, a part of the combustion gas is circulated as a high-temperature gas to the reaction furnace. This will be described in detail below with reference to FIG. Biomass crushed to several mm to several hundred mm is fed into the top of the reactor 1 through the charging port 2. At the start of operation, first, a relatively low stack of biomass is formed on the upper part of the grate 3. Subsequently, fuel and air are respectively injected from the auxiliary fuel burner A9 and the air nozzle A10, and burned at the top of the furnace to generate a high-temperature gas containing several to tens of percent oxygen. The hot gas passes through the biomass stack from the top to the bottom, and the biomass is carbonized in the order of drying → volatilization → combustion / carbonization. The combustible gas generated at that time is introduced together with the high-temperature gas into the combustion furnace 8 of the boiler that passes through the grate 3 and is connected via the connecting flue 7. The combustible gas is completely burned by the air injected from the air nozzle A10 together with the auxiliary fuel injected from the auxiliary fuel burner A9 in the combustion furnace 8 to generate a high temperature gas. A part of the hot gas is blown into the top of the reaction furnace 1 from the gas blowing port 4 through the recirculation flue 14 connecting the upper part of the combustion furnace 8 and the top of the reaction furnace 1. A biomass is continuously supplied from the inlet 2 from the time when stable volatile combustion / carbonization reaction of the biomass deposit on the upper part of the grate 3 is confirmed, and is installed at the lower level of the carbonization layer at the center of the furnace. Steam is sprayed from the mechanical steam nozzle 5 to cause the activation reaction of the carbide together with the water content of the biomass and the steam obtained by the combustion of the volatile matter. In a steady state, activation can be sufficiently performed with water vapor obtained by combustion of volatile matter and surface moisture of the biomass, so that the water vapor injection amount from the water vapor nozzle 5 can be made zero. As a result, the amount of combustible gas generated by the reaction also increases, and the combustible gas introduced from the communication flue 7 into the combustion furnace 8 also increases. Along with this, the amount of heat of the high-temperature gas blown from the gas blow-in port 4 also increases, so the auxiliary fuel injected from the auxiliary fuel burner A9 is gradually reduced to finally zero. The amount of air injected from the air nozzle A10 is such that the auxiliary fuel is completely combusted at the top of the furnace, combined with the high temperature gas sucked from the gas inlet burner, and a high temperature gas containing several percent to tens of percent oxygen. Become. This high temperature gas passes through continuously input biomass and causes the above reaction. When the height of the biomass deposition increases and the top of the layer reaches a position intermediate between the air nozzle A10 and the steam nozzle 5, the activated carbon outlet 6 is opened, and the activated carbon directly above the grate 3 is continuously taken out. As a result, the moving bed composed of the dry layer b, the volatile layer b, the combustion layer c, the carbonized layer d, the activation layer e and the activated carbon layer described in FIG. Is formed. The generation mechanism of activated carbon and the generation mechanism of combustible gas by the reaction of biomass with high-temperature gas and water vapor in the reaction furnace are the same as those described in detail in [Embodiment of the Invention]. In the steady state, the biomass having a size of several mm to several hundreds mm introduced from the top of the furnace is dried and volatilized as shown in FIGS. A moving bed composed of each layer of combustion chamber, carbonized carbon, activated carbon and activated carbon is constituted, and the activated carbon is continuously discharged from the outlet 6. On the other hand, the combustible gas introduced into the combustion furnace 8 through the grate 3 is combusted at a high temperature of 1000 ° C. or higher by the high-temperature air injected from the air nozzle B25. Therefore, chemical substances contained in building waste materials are oxidized and decomposed to make them harmless. The high-temperature combustion gas generated by the combustion generates steam at the water cooling wall 21 of the combustion furnace 8. The steam passes through the steam drum 18 and is sent to the superheater 15 to become high-temperature and high-pressure steam and is sent to the turbine. Hereinafter, components constituting the boiler will be described. 19 is a precipitation pipe, 20 is a water drum, 16 is a water supply pipe, 17 is a economizer, 22 is a high pressure ventilator, 24 is an air passage, 23 is an air preheater, 25 is an air nozzle B, 26 is an auxiliary fuel burner B , 27 is an induction fan, 29 is a flue, 28 is a gas purifier, 30 is a chimney, and 31 is a water supply connecting pipe. A part of the combustion gas generated in the boiler is supplied to the top of the reactor 1 from the injection nozzle 4 through the recirculation flue 14 by the gas recirculator 13. The hot gas then dries the wood and provides the thermal energy necessary for the water gas reaction. Water vapor generated by the combustion of volatile matter and water vapor due to the surface moisture of the biomass undergo a water-gasification reaction with the carbide. The amount of air ejected from the air nozzle A10 is adjusted so that the oxygen concentration after the high-temperature gas and the air are combined is several percent to several tens of percent to provide the high-temperature gas necessary for the reaction. By repeating the above, stable activated carbon can be continuously produced.
[0020]
【The invention's effect】
Various types of biomass, including construction waste wood, which has been conventionally troublesome according to the present invention, can be produced consistently from gasification reactors through drying to activated carbon using the thermal energy of the volatile content of the biomass. Compared to the activated carbon production equipment of
[0021]
1. Equipment cost is ½.
[0022]
2. In the steady state, the heat energy from the outside such as auxiliary fuel is zero.
[0023]
3. Since activated carbon can be produced by operating only the reactor, the number of operators is ½ (excluding utilities) compared to the conventional carbonization and activation two-furnace system.
[0024]
When the above 4, 2 and 3 are combined, the operating cost is ½ or less.
[0025]
5. Since the reactor is vertical, the site area can be greatly reduced.
[0026]
6. Can be mass-produced stably and continuously.
In summary, compared to conventional activated carbon production furnaces, activated carbon cheaper than a wide range of biomass can be mass-produced without limiting the material, and can be easily and inexpensively used for purification of exhaust gas such as dioxin adsorption.
[0027]
Further, the combustible gas generated by the water gasification reaction can generate electricity through the boiler / turbine and can be used as various heat sources.
[Brief description of the drawings]
FIG. 1 shows a conventional process for producing powdered activated carbon by carbonizing biomass, then pulverizing and rectifying and activating with steam.
FIG. 2 shows a process for producing charcoal by drying biomass with a rotary dryer and then carbonizing it by external heating in a separate carbonization cylinder.
FIG. 3 shows an example of an internal heat type vertical flow activation furnace showing a process for producing activated carbon by activating charcoal with steam.
FIG. 4 shows a rotary kiln type activated carbon production furnace showing an apparatus for consistently producing activated carbon from biomass in a rotary kiln.
Fig. 5-a Upright vertical reactor Auxiliary fuel and air are supplied to the top of the reactor to generate a high-temperature gas containing oxygen with a concentration of several to tens of percent, and the high-temperature gas converts biomass into activated carbon. Device to do.
Fig. 5-b Upright vertical reactor with product gas recirculation device In the vertical vertical reactor of Fig. 5-a, a part of the combustible gas discharged to reduce the amount of auxiliary fuel used is reduced to the top of the furnace. It was made to recirculate.
Fig. 5-c Simple continuous activated carbon production equipment (experimental furnace)
The structure of an experimental furnace produced for verification verification of the present invention is shown, in which waste wood is supplied from the top, and drying, volatilization, combustion, carbonization and activation are performed in a low oxygen atmosphere in the furnace. 1 shows an apparatus for forming activated moving beds and producing activated carbon consistently and continuously. At that time, the combustible gas generated in the furnace is combusted using auxiliary fuel (gas), and a part thereof is recirculated into the furnace to effectively use heat.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reactor 2 Biomass inlet 3 Grate 4 Recirculation gas 5 Ash outlet 6 Activated charcoal outlet 7 Communication flue 8 Combustion furnace 9 Tinder 10 Torch 11 Air fan 12 Secondary air 13 Primary air 14 Primary air control damper 15 Secondary Air conditioning damper 16 Ejector 17 Recirculation gas inlet [Fig. 6] Structure of moving bed The structure of drying, volatilization, combustion, carbonization and activation of wood in the moving bed and the change of components in each stage are shown.
FIG. 7 is a graph showing changes in mass and temperature at the height of the furnace, with the vertical axis representing the change in height (%) and the horizontal axis representing the change in temperature (° C.) or mass (% by weight).
[Fig. 8] Change in volume fraction at the height of the furnace The vertical axis shows the change in height (%), and the horizontal axis shows the volume fraction of oxygen, carbon dioxide, water vapor, carbon monoxide, hydrogen, and nitrogen. It is a graph shown by change (%).
Fig. 9-a Image of rectification effect by accumulated coarse particles Fig. 9-a shows a state in which high-temperature gas is rectified by accumulated coarse particles (biomass) in a moving bed.
[FIG. 9-b] Reaction model in the downward flow region The high-temperature gas (CO ₂ , H ₂ O, N ₂ , NO x) and the carbide reaction product gas (H ₂ , CO, CO ₂ ) are combined and The model which reacts in a layer is shown.
[Fig. 10] Activated carbon production / treatment / steam generation system Activated carbon is produced in a reaction furnace, the reducing gas generated in that process is burned in an adjacent boiler, and high-temperature and high-pressure steam is generated by the generated thermal energy to generate turbine / power generation. A system for producing electricity by sending to a machine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reactor 2 Input 3 Grate 4 Gas inlet 5 Steam nozzle 6 Activated carbon outlet 7 Connection flue 8 Combustion furnace 9 Auxiliary fuel burner A
10 Air nozzle A
DESCRIPTION OF SYMBOLS 11 Air blower 12 Air blower pipe 13 Gas recirculation machine 14 Recirculation flue 15 Superheater 16 Water supply pipe 17 Eco-container 18 Steam drum 19 Precipitation pipe 20 Water drum 21 Water cooling wall 22 Strong pressure ventilator 23 Air preheater 24 Air path 25 Air nozzle B
26 Auxiliary fuel burner B
27 Induction ventilator 28 Gas purifier 29 Chimney 30 Chimney 31 Water supply connection pipe

Claims (3)

In a reactor having a biomass inlet, an air inlet and an auxiliary fuel inlet at the top of the furnace, a grate at the bottom of the furnace, an activated carbon outlet at the top of the grate, and a combustible gas outlet at the bottom of the grate The biomass crushed to several mm to several hundred mm from the top of the furnace is sequentially added to form a moving bed in a downward flow at the top of the grate, while the volatilization of air and auxiliary fuel and / or biomass input from the top of the furnace By passing a hot gas produced by a combustion reaction for a minute and containing oxygen at a concentration of several to dozens of percent through the moving bed from above to react with biomass. An activated carbon production apparatus comprising: a dry layer, a volatile layer, a combustion layer, a carbonization layer, an activation layer, and an activated carbon layer in order from above, and taking out activated carbon from a grate upper part and a combustible gas from a grate lower part. A gas inlet is further provided in the furnace section of claim 1 and an auxiliary steam inlet is provided in the center of the furnace, and a part of the combustible gas taken out from the lower part of the grate is recirculated to the gas inlet to recirculate the top of the furnace. A high-temperature gas containing oxygen with a concentration of several to tens of percent is generated by a combustion reaction with the blown air and supplied to the moving bed to reduce or eliminate auxiliary fuel, and carbide by auxiliary steam The activated carbon production apparatus according to claim 1, wherein the activation of the activated carbon is reinforced. A gas inlet at the top of the furnace according to claim 1, an auxiliary steam inlet at the center of the furnace, and a combustion chamber connected to the combustible gas outlet at the lower part of the reactor according to claim 1, and a combustible gas in the combustion chamber. Is heated at a high temperature of 1000 ° C. or higher, a part of the combustion gas is recirculated to the gas injection port, and combined with the air from the air injection port, the oxygen has a concentration of several to tens of percent. 2. The activated carbon production apparatus according to claim 1, wherein gas is generated and supplied to the moving bed, and activation of the carbide is enhanced by auxiliary steam.

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