JPH11278822A - Simple continuous activated carbon production equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a vertical reactor, biomass is continuously supplied from the furnace top to form a downward moving bed in the furnace, and at the same time, hot gas is allowed to flow from above to below. Dry, volatilize, burn, carbonize and volatilize consistently,
Furnace for continuously producing activated carbon. SOLUTION: In a vertical reactor, a high temperature gas containing oxygen having a concentration of several% to several tens% is simultaneously flowed downward from the upper part of the furnace while continuously moving a biomass layer downward. Examples of a method for generating a high-temperature gas include combustion of auxiliary fuel at the furnace top or combustion of volatile gas of biomass generated from a furnace reaction and extracted from the furnace bottom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical down-flow reactor, in which various types of biomass, including building waste wood, are introduced from the top of the reactor to form a moving bed of biomass in the reactor. On the other hand, high-temperature gas is supplied from the furnace top, and the process from drying of biomass to the production of activated carbon is performed consistently, and the activated carbon is continuously produced (internal heating method (generated by thermal energy of volatile matter of biomass and water gasification reaction). Utilizing the heat energy of combustible gas) to provide a continuous activated carbon production apparatus.

[0002]

2. Description of the Related Art FIG. 1 shows a conventional process for producing powdered activated carbon from biomass. Conventionally, a process for producing charcoal by drying and carbonization of biomass and a process for producing activated carbon by activating charcoal with gas (steam or carbon dioxide) are usually independent of each other. FIG. 2 shows a process for producing charcoal after drying biomass with a rotary dryer and then carbonizing by external heating in a separate carbonization cylinder. FIG. 3 shows a process for producing activated carbon by activating charcoal with steam. FIG.
Fig. 1 shows an example of consistently producing activated carbon from biomass in a rotary kiln. In this case, the heating gas is obtained by burning heavy oil or gas in a combustion furnace. In the former case, the device is complicated, and in the latter case, the device becomes excessive. Therefore, in both cases, 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] The present invention forms a moving bed using biomass as a raw material in a gasification reactor,
By flowing a high-temperature gas that heats and reacts the biomass together with air from above to below, stable carbonization and
A low-cost activated carbon production system that enables the activation reaction to occur uniformly across the furnace cross section and enables continuous processes from biomass to activated carbon to be performed continuously in a structurally simple and compact reactor. The purpose is to provide.

[0004] 2. When using biomass such as construction waste wood containing chemical substances as raw material, the gas at the outlet of the reactor containing combustible gas (H ₂ , CO, CnHm, etc.) generated by the carbonization / activation reaction is burned at a high temperature of 1000 ° C. or more. After oxidizing and decomposing harmful substances in the gas to make it harmless, a part of the high-temperature gas is recirculated to the top of the gasification reactor and used for the reaction. An object of the present invention is to provide a boiler that generates a boiler.

[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 set up a grate or an equivalent activated carbon / combustible gas discharge in a lower part of a vertical reactor. A biomass is introduced from the upper part of the reactor by installing the apparatus, and a moving bed of the biomass is formed on the upper part of the grate and the equivalent apparatus. On the other hand, a high-temperature gas containing several to tens of percent of oxygen is introduced from the upper part of the furnace. When flowing through the moving bed from the top to the bottom, the high-temperature gas reacts with the biomass to form a reaction layer of drying, volatilization, combustion, carbonization, and activation in order from the top. Water vapor obtained by evaporating water and burning volatiles of biomass generated in the combustion stage is mixed with the high-temperature gas to activate char. The high-temperature gas descending in the moving bed flows down uniformly over the entire cross section of each reaction layer due to the resistance to the gas flow of the moving bed and each reaction product gas is suppressed by the descending high-temperature gas and spreads laterally. Paying attention to this, when biomass, high temperature gas and air were injected from above in an experimental furnace as shown in FIG. 5-c, the reaction in each layer was performed uniformly, and activated carbon could be taken out from the grate and the equivalent equipment After confirming this, the present invention was achieved. Note that there are the following four methods for generating and supplying the high-temperature gas.

[0006] A method of supplying auxiliary fuel and air to the top of the reactor to generate and supply a high-temperature gas containing oxygen at a concentration of several percent to several tens percent by a combustion reaction at the top of the reactor (FIG. 5A).

[0007] The auxiliary fuel is used only at the time of starting the reactor, and when the reaction in the furnace is stabilized and the moving bed starts to be formed, the auxiliary fuel is gradually reduced, and as a substitute for the auxiliary fuel, the volatile matter of the biomass is reduced. Method of use (Fig. 5-a)

[0008] When the reaction in the furnace becomes stable in the section, a method of recirculating and using a part of the combustible gas extracted from the lower part of the reactor instead of the auxiliary fuel (FIG. 5B)

As shown in FIG. 5C, the combustible gas extracted from the lower part of the furnace is burned at a high temperature of 1000 ° C. or more, and a part of the combustion gas is supplied to the furnace top together with air.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. 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. 5A and 5B.

1) Biomass (waste wood, etc.) crushed to several hundred mm to several hundred mm from a biomass inlet provided at the top of the reactor is continuously introduced into the furnace so as to be uniform over the furnace cross section. throw into.

2) The biomass charged into the furnace is dried from the top of the fire grate provided at the lower part of the reactor, from the top, the drying layer (a), the volatile layer (b), the combustion layer (c), and the carbonized layer (▲). (D) A moving bed composed of the activated layer (e) and the activated carbon layer (f) is continuously formed. (The mechanism of formation of layers (a) to (f) will be described later.)

3) A high-temperature gas containing several percent to ten and several percent of oxygen is blown into the upper part of the furnace from a gas inlet provided at the top of the reactor.

4) The high-temperature gas flows down from above in the moving bed. At that time, the biomass in the dry layer (a) at the top of the moving bed is heated and dried with high-temperature gas, settles slowly, and moves to the volatile layer (b). The high-temperature gas, which has a part of the heat retained by drying, flows down to the volatile layer while containing the moisture of the biomass in the form of water vapor, and carbonizes the dried biomass. At that time, the volatiles fly out of the biomass into the hot gas. The volatile components are oxidized and burned by the oxygen in the high-temperature gas while flowing down together with the high-temperature gas to form a combustion layer (c).
In the lower part, a part of the solid content after carbonization is also burned, and the carbonized layer
D is formed. The thermal energy and steam generated by the combustion of a part of the volatile fuel and the solid content are used for the following gasification reaction.

5) In the carbonized layer (d), part of the char (charcoal) generated by dry distillation and carbon dioxide in the high-temperature gas absorb heat energy as shown in the following equation (1) to produce carbon monoxide (combustible). Gas). C (char) + CO ₂ = 2CO−38, 200 kcal / kmol (1)

6) In the lower part of the carbonized layer, the water vapor generated by the above-mentioned drying and the burning of volatile components causes a large number of fine pores in the char (the biomass emits volatile components from the inside to the outside; Burns carbon dioxide (CO ₂ ,
CO, etc.) into the pores formed by releasing the components to the outside, causing the water gasification reaction of the following formulas (2) and (3) to further grow and develop the pores. Activate the char. _{C + H 2 O = CO +} H 2 -28,200 (2) C + 2H 2 O = CO 2 + 2H 2 -18,200 (3) (2) Also in the activation of the char (3) the thermal energy as shown in equation absorption Is done. In ordinary biomass, the amount of water vapor required for the reactions of the above formulas (2) and (3) is sufficient by the amount of water vapor obtained by drying the biomass and volatilizing the biomass, but enhances the activation of char. In such cases, steam is added from the auxiliary nozzle. In this activated layer, the char becomes activated carbon. Figure 6 shows a model of the moving floor.

7) At the upper part of the grate, a layer of activated carbon which has settled from the activated layer is formed, and is continuously taken out of the furnace from the activated carbon outlet. On the other hand, (1), (2),
The combustible gas generated by the reaction of the formula (3) is sent to the rear combustion furnace through the communication flue together with the remaining gas.

8) FIG. 7 shows a change in mass of biomass and a change in 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 suddenly decreases and the gas temperature rises sharply due to the emission of volatile components. In the activation layer, due to the water gasification reaction, the mass gradually decreases, and the gas temperature sharply decreases. When the activation is completed and the activated carbon layer is formed, both the mass and the gas temperature become constant. FIG. 8 shows changes in the composition of the high-temperature gas flowing down in the furnace depending on the furnace height. H ₂ and CO are generated from the middle of the volatile layer,
The generation increases in the activated 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, and individual solids settle down from above, while high-temperature gas (including oxygen) also flows. In the apparatus of the present invention which is charged from the furnace top and flows down in the moving bed, the accumulation of the coarse biomass and the reaction product solid in the moving bed becomes a resistance to the gas flow,
A rectifying effect is provided (see FIG. 9A). As a result, the hot gas flows down in a uniform distribution over the entire cross section of the furnace, reacts with biomass and the like, and the generated gas is forced to flow downward by being suppressed by the descending hot gas. At that time, the generated gas flows down along with the high-temperature gas while spreading in the horizontal direction due to the combination of the weak upward vector of the generated gas and the strong downward vector of the high-temperature gas (see FIG. 9B). Due to the above two factors (shown in FIGS. 9-a and 9-b), the reaction is performed uniformly over the entire furnace cross section. (On the other hand, in a conventional fixed-bed reactor, when gas flows upward, if there is a drift of high-temperature gas in the fixed bed, gasification reactions in a high-temperature-gas-rich portion become active, and combustion in that portion becomes active. As a result, the rising force of the high-temperature gas increases, and the high-temperature gas tends to concentrate on the relevant portion, causing unevenness in the reaction across the furnace cross section.) As a result, the apparatus of the present invention is shown in FIGS. Drying and volatilization in the anti-furnace,
Reactions of combustion, carbonization and activation are stably performed, and the yield of activated carbon can be increased. An auxiliary steam nozzle is a necessary condition for biomass with low volatile content and water content or for enhancing char activation, but for other biomass, sufficient steam for activation can be obtained from biomass in a steady operation state. Therefore, no auxiliary steam nozzle is required.

[0019]

DETAILED DESCRIPTION OF THE INVENTION FIG. 10 shows an embodiment of the present invention. In this embodiment, activated carbon is produced in a reaction furnace, the reducing gas generated at that time is burned in an adjacent boiler, and high-temperature, high-pressure steam is produced by the generated thermal energy, which is sent to a turbine / generator to generate electricity. to make. On the other hand, part of the combustion gas is circulated to the reactor as a high-temperature gas. The details will be described below with reference to FIG. The biomass crushed to several hundred mm to several hundred mm is introduced into the top of the reactor from the inlet. At the start of operation, first, a relatively low layer of biomass is created on the top of the grate. Next, fuel and air are injected from the auxiliary fuel burner and the air nozzle {10}, respectively, and are burned at the furnace top to generate a high-temperature gas containing several to tens of percent of oxygen. The high-temperature gas passes through the biomass lamination ▲ g ▼ from top to bottom to dry the biomass → dry distillation → volatilization →
It charifies in the order of combustion → carbonization. The combustible gas generated at that time passes through the grate together with the high-temperature gas and is introduced into the combustion furnace of the boiler connected via the communication flue. The combustible gas is completely burned by the air injected from the air nozzle (30) together with the auxiliary fuel injected from the auxiliary fuel burner (31) in the combustion furnace to generate a high-temperature gas. Part of the high-temperature gas is recirculated flue connecting the top of the combustion furnace and the top of the reactor.
Through 17 ▼, it is blown into the top of the reactor from the gas blow-in port. The biomass was continuously supplied from the inlet after the stable carbonization, volatile matter combustion, and carbonization reaction of the biomass sedimentary layer on the upper part of the grate was confirmed. Water vapor is injected from a target water vapor nozzle, and an activation reaction of carbides (chars) is performed together with water vapor obtained by burning surface water and volatiles of biomass. In the steady state, the activation can be sufficiently performed by the steam produced by the burning of the volatile matter and the surface moisture of the biomass, so that the amount of steam injected from the steam nozzle can be reduced to zero. As a result, the amount of combustible gas generated by the reaction increases, and the amount of combustible gas introduced into the combustion furnace from the communication flue also increases. Accordingly, the amount of heat of the high-temperature gas blown from the gas inlet also increases, so that the amount of auxiliary fuel injected from the auxiliary fuel burner is gradually reduced, and finally becomes zero. Air nozzle ▲ 10
The amount of air injected from ▼ completely burns the auxiliary fuel at the furnace top and combines with the high-temperature gas sucked from the gas inlet burner to become a high-temperature gas containing several to tens of percent of oxygen.
This hot gas passes downwardly through the continuously charged biomass to cause the above reaction. When the height of the biomass layer increases and the top of the layer reaches an intermediate position between the air nozzle (10) and the water vapor nozzle, an activated carbon outlet is opened and activated carbon immediately above the grate is continuously taken out.
As a result,

The dry layer (a), the volatile layer (b), the combustion layer (c), the carbonized layer (d), the activation layer (e), and the activated carbon layer (a) described with reference to FIG. A moving bed composed of f is formed. Regarding the mechanism of activated carbon and combustible gas generation by the reaction of biomass with high temperature gas and steam in the reactor,

This is the same as that described in detail in the preferred embodiments. In the steady state, a few mm
Biomass having a size of a few hundred mm is placed on the top of the grate from top to bottom as shown in Fig.5-c and Fig.6, drying (a), volatilization (b), combustion (c), carbonization (d), and activation. The moving bed is composed of the layers of (e) and (c), and the activated carbon is continuously discharged from the outlet. On the other hand, the combustible gas introduced into the combustion furnace after passing through the grate is discharged by the high-temperature air injected from the air nozzle (30).
Combustion at a high temperature of 0 ° C or higher. For this reason, chemical substances contained in construction waste and the like are oxidized and decomposed to render them harmless. The high-temperature combustion gas generated by the combustion is the water-cooled wall of the combustion furnace (26).
Generates steam. The steam is sent to a superheater (18) via a steam drum (23), and becomes high-temperature and high-pressure steam and sent to a turbine. Hereinafter, components constituting the boiler will be described.
[24] is a downcomer, [25] is a water drum, [21] is a water supply pipe, [22] is a conserver, [27] is a high-pressure ventilator, and [2]
9 is an airway, 28 is an air preheater, 30 is an air nozzle, 31 is an auxiliary fuel burner, 32 is an induction ventilator, 34 is a flue, and 33 is a gas cleaner. Equipment, ▲ 35
▼ is a chimney, and ▲ 36 is a water supply connection pipe. Part of the combustion gas generated in the boiler passes through a recirculation flue (17) and is injected into the top of the reactor from an injection nozzle by a gas recirculator (16). At this time, the high-temperature gas dries and carbonizes the wood, and provides thermal energy required for the water gas reaction. The water vapor generated by the combustion of the volatile matter and the water vapor generated by the surface moisture of the biomass perform a water gasification reaction with the char. The amount of air ejected from the air nozzle (10) is adjusted so that the oxygen concentration after the high-temperature gas and the air are combined becomes several percent to several tens percent, thereby providing a high-temperature gas necessary for the reaction. By repeating the above, stable continuous production of activated carbon becomes possible.

[0020]

According to the present invention, various types of biomass, including building waste wood, which had been troublesome in the past, can be used in a gasification reactor from drying to activated carbon by utilizing the thermal energy of the volatile matter held by the biomass. Because it can be manufactured, compared to conventional activated carbon manufacturing equipment,

Equipment costs are halved.

In a steady state, external heat energy such as auxiliary fuel is zero.

Since activated carbon can be produced only by the operation of the reaction furnace, the number of operators (except for utilities) is reduced by half compared to the conventional two-furnace system of carbonization and activation.

When the above is combined, the operating cost is also reduced by half.
It is as follows.

Since the reactor is vertical, the site area can be greatly reduced.

Mass production can be performed continuously and stably. In summary, compared to the conventional activated carbon production furnace, activated carbon can be mass-produced inexpensively from a wide range of biomass without limiting materials, and can be easily and inexpensively used for purification of exhaust gas such as dioxin adsorption.

The combustible gas generated by the water gasification reaction can generate electricity through a boiler / turbine and can be used as various heat sources.

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[Procedure amendment]

[Submission date] January 6, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 shows a conventional process for producing powdered activated carbon after carbonizing biomass, pulverizing and rectifying the activated biomass, and activating with steam.

FIG. 2 shows a process of producing charcoal after biomass is dried by a rotary dryer and then carbonized by external heating in a separate carbonization tower.

FIG. 3 shows an example of an internal heat type vertical fluidized activation furnace in which charcoal is activated with steam to produce activated carbon.

FIG. 4 shows an apparatus for consistently producing activated carbon from biomass in a rotary kiln using a rotary kiln.

Fig. 5-a Vertical upright reactor Auxiliary fuel and air are supplied to the top of the reactor to produce several percent to several tens percent.
A device that generates a high-temperature gas containing oxygen at a concentration of 0.1% and converts biomass into activated carbon using the high-temperature gas.

FIG. 5B is a vertical reactor having a product gas recirculation device. In the vertical reactor shown in FIG. 5-a, a part of combustible gas discharged to reduce the amount of auxiliary fuel used is transferred to the furnace top. Recirculated to

FIG. 5-c shows a simplified continuous activated carbon production apparatus (experimental furnace) showing the structure of an experimental furnace produced for the purpose of verifying the demonstration of the present invention, in which waste wood is supplied from the top and low oxygen is supplied in the furnace. 1 shows an apparatus for forming a downward moving bed that performs drying, volatilization, combustion, carbonization, and activation under an atmosphere, and consistently and continuously manufactures activated carbon. At that time, the combustible gas generated in the furnace is burned using an auxiliary fuel (gas), and a part of the combustible gas is recirculated into the furnace to effectively use the heat.

[Explanation of symbols] Reactor Biomass inlet Grate Recirculated gas Ash outlet Activated carbon outlet Communication flue Combustion furnace Crate ▲ 10 ▼ Torch ▲ 11 ▼ Air fan ▲ 12 ▼ Secondary air ▲ 13 ▼ Primary air ▲ 14 ▼ Primary Air conditioning damper ▲ 15 ▼ Secondary air conditioning damper ▲ 16 ▼ Ejector ▲ 17 ▼ Recirculation gas inlet

FIG. 6 shows the structure of drying, volatilization, combustion, carbonization, and activation of wood on the moving bed, and the component changes at each stage.

FIG. 7 is a graph showing changes in mass and temperature at the height position of the furnace, where the vertical axis indicates changes in height (%) and the horizontal axis indicates changes in temperature (° C.) or mass (% by weight).

FIG. 8: Change in volume fraction at the height position of the furnace The vertical axis indicates the change in height (%), and the horizontal axis indicates the volume fraction of oxygen, carbon dioxide, water vapor, carbon monoxide, hydrogen, and nitrogen. It is a graph shown by a change (%).

FIG. 9-a is a rectification effect due to accumulated coarse particles. A high-temperature gas is rectified by accumulated coarse particles (biomass) in a moving bed.

FIG. 9-b: Reaction model in a downflow region High-temperature gas (CO ₂ , H ₂ O, N ₂ , Nox) and reaction product gas (H ₂ , CO, CO ₂ ) of char (carbide) are combined. Here is a model that reacts in the next layer.

Fig. 10 Activated carbon production / treatment / steam generation system Activated carbon is produced in a reactor, and the reducing gas generated at that time is burned in an adjacent boiler, and high-temperature, high-pressure steam is generated by the generated thermal energy, and turbine / power generation is performed. Shows a system that sends electricity to the machine to produce electricity.

[Explanation of symbols] Reactor inlet Grate Gas inlet Steam nozzle Activated carbon outlet Communication flue Combustion furnace Auxiliary fuel burner ▲ 10 ▼ Air nozzle ▲ 11 ▼ Air blower ▲ 12 ▼ ‥ ▲ 13 ▼ Air blower pipe ▲ 14 ▼ ▲ ▲ 15 ▼ １５ ▲ 16 ▼ Gas recirculator ▲ 17 ▼ Recirculation flue ▲ 18 ▼ Superheater ▲ 19 ▼ ‥ ▲ 20 ▼ ‥ ▲ 21 ▼ Water pipe ▲ 22 ▼ Economizer ▲ 23 ▼ Steam drum ▲ 24 ▼ Downcomer ▲ 25 ▼ Water drum ▲ 26 ▼ Water cooling wall ▲ 27 ▼ High pressure ventilator ▲ 28 ▼ Air preheater ▲ 29 ▼ Airway ▲ 30 ▼ Air nozzle ▲ 31 ▼ Auxiliary fuel burner ▲ 32 ▼ Induced ventilator ▲ 33 ▼ Gas purifier ▲ 34 ▼ Flue ▲ 35 ▼ Chimney ▲ 36 ▼ Water supply connection pipe

 ──────────────────────────────────────────────────続 き Continuing from the front page (71) Applicant 593095232 Nagaishi High-Tech Co., Ltd. 2165 Kaizu-cho, Isahaya-shi, Nagasaki (72) Inventor Masayasu Sakai 536, Aiba-cho, Nagasaki-shi Nagasaki Institute of Science and Technology

Claims (3)

[Claims] 1. An inlet, an air inlet, and an auxiliary fuel inlet for biomass (wood, etc.) at the furnace top, a grate at the lower part of the furnace, and a solid matter (activated carbon, etc.) outlet at the upper part of the grate.
In a reactor with a gas (combustible gas, etc.) outlet at the bottom of the grate, biomass crushed several millimeters to several hundreds mm from the top of the furnace is sequentially charged to form a moving bed with a downward flow at the top of the grate On the other hand, a high-temperature gas generated by a combustion reaction of air and auxiliary fuel and / or volatile matter of biomass introduced from the furnace top and containing oxygen having a concentration of several to ten and several percent is passed through the moving bed. Pass from top to bottom,
By reacting with biomass, the downward moving bed is formed from a dry layer, a volatile layer, a combustion layer, a carbonized layer, an activated layer and an activated carbon layer in order from the top, and activated carbon is supplied from the upper part of the grate and combustible gas is supplied from the lower part of the grate. Activated carbon production equipment characterized by taking out. 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 produced in the furnace is removed from below, the constituents of the floor move downward. Therefore, it is called a downward moving floor. 2. A gas inlet at the furnace top according to claim 1, further comprising:
An auxiliary steam inlet is provided at 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, and the combustion reaction with the blown air at the top of the furnace causes a reaction within a few percent. A high-temperature gas containing oxygen at a concentration of several percent is generated and supplied to a moving bed to reduce or eliminate auxiliary fuel and enhance char (carbide) activation by auxiliary steam. The activated carbon production apparatus according to claim 1. 3. A combustion chamber connected to a gas inlet at the top of the furnace of claim 1, an auxiliary steam inlet at the center of the furnace, and a combustible gas outlet at the lower part of the reactor of claim 1; The combustible gas is burned at a high temperature of 1000 ° C. or more in the combustion chamber, and a part of the combustion gas is recirculated to the gas inlet, and combined with the air from the air inlet to within 10% to 10%. 2. The activated carbon production apparatus according to claim 1, wherein a high-temperature gas having a concentration of oxygen is generated and supplied to a moving bed, and the activation of char is enhanced by auxiliary steam.