JPS58140311A - Manufacture of molded activated carbon using wood as starting material - Google Patents

Abstract

PURPOSE:To obtain woody molded activated carbon of high quality without using a binder by crushing wood as a starting material, extrusion-molding the crushed wood after adjusting the water content, carbonizing the moldings by heating, and carrying out activation in a specified atmosphere. CONSTITUTION:Woody waste, etc. are crushed and classified. This crushed starting material having a prescribed grain size is dried to adjust the water content to about 12-18wt%, and the dried material is extrusion-molded at high temp. and pressure with a continuous compression molding machine or the like. The moldings are cut to form woody pellets, and the pellets are carbonized by heating at about 400-700 deg.C. The carbonized pellets are activated in a steam atmosphere at about 800-1,000 deg.C in a rotary kiln or the like to grow the porous structure of the pellets. By this method woody molded activated carbon having many pores and high adsorbing power is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing shaped activated carbon using wood as a raw material.

Used for gas processing, liquid processing, etc. In the conventional method for producing p-type activated carbon, a caking agent or binder (tar, pitch, mesh cloth, etc.) is added to the pulverized raw material, and the steps of kneading, carbonization, activation, pickling, drying, and sorting are carried out. It was manufactured by.

However, in the conventional method for producing shaped activated carbon using wood as the raw material, binder is added to the raw material, so when mixing the granular raw material and liquid binder, air in the raw material is removed. It was necessary to increase the density by degassing, but sufficient degassing could not be achieved even by using a screw kneader or the like equipped with a vacuum device. In addition, the binder is mainly composed of volatile substances, and during carbonization, the emitted components create relatively large pores within the molded product, which causes a problem in that the strength and density of the molded product decreases. . Furthermore, depending on the type of binder, there is a problem in that harmful gases such as M-member oxides are generated during carbonization.

The present invention has been made by focusing on the problems described in E in the conventional method for producing shaped activated carbon using wood as a raw material, and has made it possible to produce shaped activated carbon without using a binder. The aim is to solve the above problems by doing so.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings showing embodiments thereof.

First, the raw material, which is wood waste, is first crushed using a coarse crusher such as a chipper to produce wood pieces with a maximum length of 500 mm and a maximum diameter of 100 mm, which are used as the raw material. In addition,
In the case of raw materials containing iron pieces, such as shavings and scraps, the iron pieces are removed by a magnetic separator after the primary crushing.

Next, the raw material is subjected to secondary crushing using an impact crusher to obtain crushed raw material in the form of small pieces or powder having a catfish size of 30 mm or less and a maximum diameter of 5 mm or less. Note that if the crushed raw material contains foreign matter such as stone chips, the foreign matter is removed by air sorting. Wind sorting is performed by moving the crushed raw material by wind power through a transport pipe equipped with a trap, and collecting foreign matter with a large specific gravity in the trap.

The crushed raw material is then moisture-adjusted. In moisture adjustment, the crushed raw material is dried in a rotary kiln dryer so that the moisture content becomes 12 to 18% by weight. In addition, before moisture adjustment, the moisture content when raw wood is used as raw material is usually 45-5511! :% by weight, the moisture content of waste wood from the lumber process is 20 to 30%, and the moisture content of construction waste wood is 10%.
~20 Juren%. Therefore, in the case of construction waste materials, there is almost no need for drying.

After adjusting the moisture content, the crushed raw material is sieved and sorted, and the coarse particles contained therein are sent back to secondary crushing. The returned coarse particles are crushed again for a second time, but this time the moisture content has been adjusted and the pieces have been dried, so they are reliably crushed to a predetermined size.

The crushed raw material of a suitable size that has passed through the sorting process is stored in a storage container, and is supplied in a fixed amount to a continuous compression molding machine by a quantitative feeder. A continuous compression molding machine has a cylindrical die rotated by a motor, a plurality of rolls placed in contact with the inner diameter of the die, and a spreader that evenly distributes the crushed raw material between the rolls. . The crushed raw material introduced into the die is caught between the inner diameter portion of the die and the roll, and is continuously extruded toward the outer periphery through die holes provided radially in the die. The diameter of the chair hole is 5-7mm.
The cylindrical molded product extruded from the die hole is cut into an appropriate length by a cutter provided close to the outer periphery of the die.

When compressed between a die and a roll and passed through a die hole, the temperature of the crushed raw material reaches 150 to 200°C and the pressure reaches 400 to 8000 kg/cm'. For this reason, the crushed raw material is plasticized by 6R and self-caking due to the action of lignin, resin, etc. contained in the raw material. The molded product thus caked is compressed to a high density of approximately 1.4 g/cm 3 . In addition, when compression molding is performed under high temperature and high pressure as described in 1-, when the raw material passes through the die hole, resin components such as wax ooze out onto the surface, creating a glossy film on the surface of the molded product.
Ru. If molding is performed at low temperatures and pressures that do not produce a glossy film, the bonding of the molded product will be weak and cracks will occur on one surface, reducing the quality of the activated carbon that is the most bonded product. During the above-mentioned molding process, the moisture content in the raw material is reduced by 3 to 5 percent. Wood pellets made by cutting the molded product are air-cooled before moving on to the next carbonization process, which further reduces moisture content.
Strength increases.

The air-cooled wood pellets are sent to the carbonization process. In the carbonization process, wood pellets are heated to 400-700°C in a furnace with little or no oxygen. As a result, the wood pellets are carbonized and the volume increases to 40~
It shrinks to 50% and becomes a charcoal pellet. Note that the carbonization time is very short because finely cut charcoal pellets are carbonized. Moreover, the yield of charcoal pellets to wood pellets was 30 to 45% (weight ratio). This is because moisture and volatile content in the wood pellets are lost, and some of the wood pellets are thermally decomposed. The carbonized pellet has a porous structure with voids formed in areas where volatile substances are lost during carbonization and areas through which volatile substances have passed.

The carbonized pellets that have undergone carbonization are transferred to an external heating rotor. The activation time is 10 to 30 minutes, and the i of the steam blown in is 0.5 to 30 minutes.
2.5 kg (steam)/kg i” charcoal pellet) was suitable. Through this activation process, the porous structure of the carbonized pellet was further developed, and an extremely large number of pores ranging from small pores to relatively large pores were formed. Activated carbon with high adsorption properties can be obtained.

The activated carbon is cooled in an inert atmosphere, and then sorted to remove powdered activated carbon to form a final product (the powder removed at this time is used as powdered activated carbon).

Note that the gas mainly composed of H2 and CO generated in the carbonization process and the activation process is recovered and used as a fuel gas for carbonization and activation.

As described in 1-, in the present invention, before carbonizing the raw material,
Wood pellets are formed using the plasticization and self-caking properties of wood raw materials under high temperature and high pressure, and activated carbon with high adsorption properties is obtained by carbonizing and activating the wood pellets.

Therefore, there is no need to use a binder, which was conventionally required during molding.

Therefore, the conventional problems of insufficient degassing and a decrease in strength and density due to volatilization of volatile matter, and the generation of toxic gases, are eliminated. Therefore, high quality shaped activated carbon having sufficient mechanical strength and density can be obtained. Furthermore, since the material is shaped before carbonization, there is no risk of the raw material igniting during the drying and shaping process.

In addition, wood raw materials include processed waste wood from sawmilling, thinned wood,
There are construction waste materials, etc., but even if you add bark to these materials, 50%
(dry weight %) or less, the properties of the wood pellet did not deteriorate when the wood pellet was formed by the method of the present invention, and a high-quality formed activated carbon could be obtained.

As explained above, according to the present invention, wood as a raw material is crushed to obtain crushed raw material with a predetermined particle size, the crushed raw material is dried to adjust the moisture content, and the crushed raw material after moisture adjustment is heated at high temperature.
Wood pellets are made by extrusion molding and cutting under high pressure, then the wood pellets are heated and carbonized to make carbonized pellets, and the carbonized pellets are activated in a high-temperature steam atmosphere to make activated carbon, making it easy to produce high-quality wood shaped activated carbon. The advantage is that it can be manufactured through multiple steps.

[Brief explanation of the drawing]

The figure is a block diagram showing the manufacturing process according to the present invention. Patent applicant: Japan Steel Works, Ltd. Agent: Patent attorney: Toshiyuki Miyauchi

Claims (1)

[Scope of Claims] 1. The raw material wood is crushed to obtain a crushed raw material with a predetermined particle size, the crushed raw material is dried to adjust the moisture content, and the crushed raw material after moisture adjustment is extruded at high temperature and high pressure and cut. A method for producing shaped activated carbon using wood as a raw material, in which the wood pellets are made into wood pellets, the wood pellets are then heated and carbonized to make carbonized pellets, and the carbonized pellets are activated in a high-temperature steam atmosphere to make activated carbon. 2. A method for producing shaped activated carbon using wood as a raw material according to claim 1, wherein the raw material wood contains 50% (dry weight %) or less of bark.