JPH0139967B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a regeneration method and apparatus for reusing waste activated carbon with a high moisture content used for water treatment and the like. Therefore, it is characterized in that waste activated carbon, which has a particularly high moisture content, is efficiently reactivated using a continuous flow method, and the heat generated in the deodorizing furnace is reused in the dryer, which particularly enhances the energy saving effect. be.

Currently, activated carbon is widely used as an adsorbent in water treatment and the like, but when a certain amount of adsorption is reached, it is desirable to take out the waste activated carbon, regenerate it, and recycle it. As a method for regenerating waste activated carbon, many methods using fluidized beds have been proposed in the past, but all of them have a high fluidized bed height, and both vertical and horizontal multi-stage systems have separate sections separated by overflow pipes or partition walls. The tank is designed to ensure complete mixing. Therefore, it is necessary to make the residence time considerably longer, but this is probably due to the influence of the design concept of the activation furnace for producing activated carbon.The amount of retained activated carbon during regeneration is large and the height of the fluidized bed is high. Therefore, defects that increase wear loss are noticeable.

As a means to solve such technical problems, for example, a two-stage continuous flow regenerator (Japanese Patent Application Laid-open No.
18494) are presented. This is a method in which a vertical reactor has two fluidized beds, upper and lower, where the upper stage performs preheating, drying, and carbonization (roasting), and the lower stage regenerates the waste activated carbon used for water treatment. If it is directly charged into a fluidized bed at a high temperature, it will become lumpy and a good fluidization state will not be obtained, and therefore drying and carbonization will be insufficient, and sufficient effects will not be achieved in the next regeneration chamber.

In order to solve this problem, the present inventors separated the drying and carbonization steps from the regeneration step, and adopted a rotary kiln method or a special moving bed method for the former, thereby producing a product with a very high moisture content. We sought a method that would provide a mechanism and capacity that would provide sufficient effects even when using waste activated carbon, which tends to stick, and that would further enhance the functionality of the latter fluidized bed for regeneration. The high temperature waste gas used in the regeneration process is dried and
It is used in the carbonization process, but it has a strong odor and cannot be released as it is, so it is re-burned with fuel and deodorized before being released. However, by circulating and reusing the afterburned gas for indirect heating in the drying/carbonization process, we have discovered that when the moisture content of waste activated carbon is high, a significant energy saving effect can be obtained due to the large calorific value of the afterburned gas, and we have developed the present invention. reached.

That is, in the waste activated carbon regeneration process, which consists of a regeneration furnace consisting of a dryer, a combustion chamber, and a regeneration chamber, and a deodorizing furnace, the regeneration furnace is an annular regeneration furnace with two vertical concentric cylindrical partition walls and a bottom section separated by a perforated plate rectifier. It has a regeneration chamber, and the annular rectifier is partitioned at one point by a diametrical weir. High-temperature regeneration gas is blown into the regeneration chamber from the lower combustion chamber through a perforated plate to form an activated carbon fluidized bed, and the height of the regenerated coal outlet can be adjusted to adjust the fluidized bed height and residence time. It's very quiet. In addition, the gas emitted from the regeneration furnace was led to a dryer, where it was dried in countercurrent to the waste activated carbon, and then combusted in a deodorizing furnace.The high-temperature re-combustion gas was led to the jacket of the dryer so that it could be used for drying the waste activated carbon. This is a waste activated carbon regeneration device characterized by the following.

The present invention will now be explained in more detail with reference to the illustrated drawings. FIG. 1 shows one example of the present invention, and shows a configuration consisting of a combustion furnace, a regeneration furnace, a dryer, and a deodorizing furnace. 1 is a rotary kiln type dryer with internal and external heating, and waste activated carbon is charged from 2.
After being dried by gas 3 generated from the regeneration furnace 4
It is then fed into the regeneration furnace 5. A cross-sectional view of the AA section is shown in FIG. 2. The regeneration furnace consists of a cylindrical outer shell 5 made of refractory material, a low cylindrical part 6 in the center, and a perforated plate rectifier 7.The annular part serves as a regeneration chamber, and activated carbon flows over the rectifier. Layer 8 is formed. There is a weir 9 in the regeneration chamber, and the waste activated carbon charged from 4 falls through the regeneration chamber and falls into the area 10, forming a fluidized bed 8 while being regenerated by the combustion gas blown through the rectifier and collecting the regenerated activated carbon. It is taken out from the outlet 11.

The combustion chamber 12 includes a burner 13, a fuel inlet 14,
Consisting of an air inlet 15 and a steam inlet 16,
The gas consisting of combustion gas and steam is blown into the activated carbon bed 8 of the regeneration chamber through the rectifier 7.

The combustion gas used for regeneration is blown into the interior 17 of a rotary kiln type dryer through 3, and is dried in countercurrent to the waste activated carbon containing moisture, which moves while being stirred as the kiln rotates. . The gas that exits the dryer outlet 18 usually has a strong odor because it contains components desorbed from the activated carbon, and cannot be released as it is, so it is led to the deodorizing furnace 19 and sent to the burner 20.
It mixes with the combustion gas generated by the gas and deodorizes it in a high temperature state. 21 is a fuel inlet, and 22 is an air inlet. The high-temperature deodorizing gas passes through the jacket part 23 of the dryer, uses the waste heat to dry the waste activated carbon, and then preheats the air for blowing into the burner in the heat exchanger 24 before being released. Further, the air entering the system passes through the blower 25, is preheated by the heat exchanger 24, and is then blown into the burners 13 and 20 of the regeneration furnace and the deodorizing furnace.

FIG. 3 shows the configuration when a moving bed dryer is used as the dryer, and the configuration is the same as that in FIG. 1 except for the dryer and the deodorizing furnace. Dryer 26
It has a cylindrical shape with a rounded bottom and has an umbrella-type dispersion plate 27 inside. The waste activated carbon containing moisture enters from 28, falls onto the distribution plate, and is dried by the combustion gas used for regeneration while falling along the distribution plate. The dried waste activated carbon is fed into the regeneration furnace 5 through 29. The gas exiting the dryer outlet 30 contains components desorbed from the activated carbon, so it usually has a strong odor and cannot be released as it is, so it is led to the deodorizing furnace 31 and mixed with the combustion gas generated by the burner 32, where it is heated to a high temperature state. Deodorizes as. 33 is a fuel inlet, and 34 is an air inlet. The high-temperature deodorizing gas passes through the jacket 35 of the dryer, reuses the waste heat for drying the waste activated carbon, and then preheats the air for blowing into the burner in the heat exchanger 24 before being released.

Next, we will discuss the main unit operations. The waste activated carbon dried in the regeneration furnace is placed near the weir in the annular regeneration chamber, moves while forming a fluidized bed with the combustion gas blown through the rectifier, reaches the opposite side of the weir, and is taken out. . This is based on many years of experience: (1) In a fluidized bed of granular coal, heat and mass transfer occur rapidly at a bed height of 10 mm above the gas rectifier. (2) When the height of the fluidized bed is low, back mixing of particles hardly occurs even if the average particle movement speed of the fluidized bed is small. Therefore, even if the treatment is performed using a fluidized bed without partition walls, a state close to a complete piston flow will be achieved. (3) Regeneration using a piston flow fluidized bed is the most homogeneous and highly efficient. This regeneration reactor was designed based on these findings.

The reclaimed coal outlet can be adjusted in height, which allows the fluidized bed height to be adjusted and the residence time and performance recovery rate to be controlled.

Waste activated carbon is in various states depending on the manner in which it is used, but those for water treatment, which are used in the largest quantities and require regeneration, are usually easy to regenerate and require a relatively short regeneration time. When a fluidized bed is formed by blowing high-temperature gas containing steam or carbon dioxide, effective regeneration can be achieved with a bed height of several 10 mm.
The playback speed of the portion above this level decreases. Also, if the bed height is that high, the flow state will be mild,
Particle wear is low, and the state is close to perfect piston flow, resulting in high regeneration yield and high homogeneity. Therefore, in the regeneration furnace of the present invention, extremely excellent effects can be obtained in the regeneration of activated carbon used in water treatment by lowering the bed height of the fluidized bed for regeneration.

In order to feed waste activated carbon into a regeneration furnace, it must be dried beforehand. However, waste activated carbon used for water treatment usually has an extremely high moisture content and is often slightly sticky. A fluidized bed method is often used to efficiently dry activated carbon, but activated carbon with such properties tends to form lumps and is difficult to dry uniformly. From this point of view, in the present application, a rotary kiln type dryer is used in FIG. 1. This means that even when waste activated carbon with an extremely high moisture content is used, it is prevented from forming into lumps due to agitation caused by the rotation of the kiln, and good contact between the drying gas and the activated carbon allows for uniform drying. Combined with the heating, drying is further promoted. Particularly in zones with high moisture content, indirect heating can also have a considerable effect.

FIG. 3 shows a dryer using a moving bed method, and in addition to direct heating of the moving bed near the umbrella-type dispersion plate, drying is further promoted by indirect heating by high-temperature deodorizing gas from the jacket. However, this type of dryer has the greatest drying effect due to direct heating near the umbrella-type dispersion plate, so it is suitable when the moisture content of the waste activated carbon is slightly lower than that of the rotary kiln type.

Furthermore, having a high energy saving effect is one of the most important structural requirements in the structure of the present invention.
That is, the gas used for regeneration at approximately 1000°C generated in the combustion chamber maintains a temperature of approximately 700°C at the outlet of the regeneration furnace and is led to the dryer. The temperature of the dryer outlet gas used for countercurrent drying of waste activated carbon depends on the moisture content of the waste activated carbon, but as an example, the gas that has reached about 400℃ is heated again to 750℃ or higher in a deodorizing furnace. It is introduced into the dryer jacket and reused for drying, reaching a temperature of approximately 500°C, and is further used in a heat exchanger to preheat the air for blowing into the burner, reaching a temperature of 420°C to 450°C.
Released at °C. Since the gas generated from waste activated carbon dryers usually has a strong odor, deodorization by re-combustion is inevitable. In the configuration of the present invention, a fuel saving effect of about 20% was obtained by using the high temperature deodorizing gas for drying and preheating the air for blowing into the burner, and also using the regeneration furnace gas for drying.

As detailed above, in the regeneration of waste activated carbon,
The effects of the present invention are that a homogeneous recycled coal with little wear and a high performance recovery rate can be obtained, and that a high energy saving effect can be obtained by recycling waste gas.

The present invention will be described below with reference to Examples, but these Examples do not limit the present invention in any way.

Example The physical properties and amount of fuel used for waste activated carbon and recycled carbon used in the treatment of wastewater generated in the food industry are as follows.

●Waste activated carbon processing amount 55Kg/hr (dry weight conversion) 〃 Moisture content 96.9% (dry weight basis) 〃 Adsorption capacity (iodine)
555mg/g 〃 〃 (methylene blue)
80c.c./g ●Dryer outlet moisture 33.3% (dry basis) ●Regenerated coal production amount 45.7Kg/hr 〃 Adsorption capacity (iodine)
1034mg/g 〃 〃 (methylene blue)
180 c.c./g ●Amount of kerosene used: 0.44/Kg Regenerated coal Comparative example The waste activated carbon used in the above example was directly charged into a regeneration furnace, and the deodorizing furnace gas was directly discharged without passing through a heat exchanger.

●Amount of waste activated carbon processed 55Kg/hr (dry weight conversion) ●Amount of recycled carbon produced 46.0Kg/hr 〃 Adsorption capacity (iodine)
1025mg/g 〃 〃 (methylene blue)
180c.c./g ●Amount of kerosene used: 0.55/Kg Regenerated coal In the example, an energy saving effect of about 20% is obtained compared to the comparative example, and the adsorption capacity is also slightly improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing the configuration of a rotary kiln type dryer used as the dryer in the present invention, and FIG. 2 is a section A-A of the regeneration furnace shown in FIG. A cross-sectional view is shown. FIG. 3 is a vertical sectional view showing the structure of a moving bed dryer having an umbrella-type dispersion plate as the dryer.

Claims (1)

[Claims] 1. A regeneration furnace comprising a dryer, a combustion chamber, and a regeneration chamber;
In the waste activated carbon regeneration process consisting of a deodorizing furnace. The regeneration furnace has an annular regeneration chamber separated by two vertical concentric cylindrical partition walls and a perforated plate rectifier at the bottom. is injected into the regeneration chamber from the lower combustion chamber through a perforated plate straightener to form an activated carbon fluidized bed, and the height of the regenerated coal outlet is adjustable so that the height and residence time of the fluidized bed can be adjusted. The gas exiting the regeneration furnace is led to a dryer, where it is dried in countercurrent to the waste activated carbon, and then combusted in a deodorizing furnace.The high-temperature re-burned gas is led to the jacket of the dryer and is configured so that it can be used for drying the waste activated carbon. Waste activated carbon regeneration equipment. 2. The waste activated carbon regeneration apparatus according to claim 1, wherein the dryer is a rotary kiln type dryer using both internal and external heating. 3. The waste activated carbon regeneration apparatus according to claim 1, wherein the dryer is a vertical moving bed type dryer having an umbrella-shaped dispersion plate inside and a jacket outside.