JPS58213614A - Preparation of formed active coke for desulfurization and denitration - Google Patents

Abstract

PURPOSE:To prepare the titled coke having high strength and porosity and excellent quality, in high yield, by carbonizing formed raw material made mainly from semi-coke in an internal heating rotary kiln in reducing atmosphere, and activating the carbonized porduct. CONSTITUTION:A mixture consisting of (A) about 50-70wt% of semi-coke (preferably obtained by the low-temperature carbonization of coal, etc. at about 400-700 deg.C), (B) about 20-35wt% of coal, and (C) about 5-15wt% of a binder such as soft pitch, is formed to a desired form. The formed material is carbonized in an internal heating rotary kiln having reducing inner atmosphere while introducing a non-oxidizing gas (e.g. hot gas produced by burning a fuel gas with about 0.4-0.7times volume of air necessary for the complete combustion of the fuel gas). The obtained formed coke is activated with steam using a vertical-type multistage furnace, etc. to obtain the formed active coke.

Description

DETAILED DESCRIPTION OF THE INVENTION Many wet or dry desulfurization and denitrification processes are known as methods for removing sulfur oxides and nitrogen oxides contained in various waste gases. Among these desulfurization and denitration processes, in the dry method, activated carbon in the form of granules or molds is widely used as an adsorption-reducing agent because it is easily available and has excellent adsorption-reduction performance.However, activated carbon has poor pressure resistance, wear resistance, and resistance. It has low impact resistance, and suffers from large wear and tear when repeatedly used for adsorption and regeneration in moving bed or fluidized bed processes, which poses economical problems.

Molded activated coke, which has a smaller specific surface area than activated carbon but has higher strength and superior desulfurization and denitrification ability, is attracting attention as a way to improve the disadvantages of activated carbon (Japanese Patent Application No. 174566/1983, etc.). ).

The present invention relates to a method for efficiently producing molded activated coke with high strength and suitable for desulfurization and denitrification using coal as the main raw material.

The above-mentioned activated carbon or activated coke is produced by preparing carbon material raw materials, granulating or molding them, subjecting them to carbonization degassing treatment, and then activating them. There are various types of equipment used in this carbonization process, such as a fixed bed, a moving bed, and a fluidized bed, and the heating methods include an internal heating method using direct heating and an external heating method using indirect heating. Comparing the characteristics of the two-leg heating method, we find that in the case of the internal heating method, the fuel is combusted internally, resulting in good thermal efficiency and a product with high porosity, but in order to burn the fuel sufficiently, excess air or Since oxygen is used, the inside of the carbonization furnace becomes an oxidizing atmosphere, which has the fatal disadvantage that the yield of the product is poor and the strength of the obtained product is low. On the other hand, in the case of an external heating type, the inside of the carbonization furnace can be maintained in a reducing atmosphere by using the gas generated from the molded product, so it is possible to obtain high-strength products with a good yield, but the thermal efficiency is poor and the product quality is low. The disadvantage is that it is difficult to obtain a product with high activity due to its low porosity. Usually, fluidized bed furnaces, He
Rreshoff-type multi-stage bed furnaces, rotary kilns, etc. are used, and among them, rotary kilns can continuously carbonize large amounts of briquette coal, and the operating conditions can be adjusted to
It is the most commonly used because it can be A rotary kill is usually an internal combustion type, and in order to increase thermal efficiency, it is operated at an air ratio that allows sufficient combustion of fuel, so the inside of the furnace is an oxidizing atmosphere.

Therefore, if you dislike oxidizing atmosphere, use the external heating type 0-11.
J-*ru/ has been adopted.

An object of the present invention is to provide a method for producing shaped activated coke for desulfurization and denitrification, which improves the drawbacks of the conventional methods.

That is, the present invention uses semi-formed coke produced from various types of coal as the main raw material, molds a mixture containing coal and a binder, and carbonizes the molded product in a reducing atmosphere using an internal heating rotary kiln. This is a method for producing shaped activated coke for desulfurization and denitrification, which is characterized in that it is then activated.

The semi-formed coke, which is the main raw material used in the method of the present invention, is made of coal, which is pretreated if necessary, and then
Semi-formed coke with high activity obtained by carbonization at a low temperature of 0 to 700°C is preferred.

Although this semi-formed coke still has some caking properties, in order to caking it and obtain high-strength molded coke, it is necessary to use coking coal that has caking properties as an auxiliary raw material. and Soft Pitch Gin binder, the caking property is adjusted so that the molded product is easy to mold, does not weld during carbonization treatment, and maintains high strength. Mold into.

Although the mixing ratio of raw materials varies depending on the type of raw materials used, it is desirable to determine the types and amounts of auxiliary raw materials so that the loga index (JIS M2SO4) of the raw material mixture is in the range of about 20 to 30. Approximately 50-75% by weight of main raw materials
, 20 to 35% by weight of coal for adjusting the caking property, and 5 to 15% by weight of a binder such as soft pitch.

Next, the molded raw material mixture is supplied to an internally heated rotary kiln maintained in a reducing atmosphere and carbonized to form molded coke. In order to maintain a reducing atmosphere inside an internally heated rotary kiln, the oxygen partial pressure inside the furnace can be lowered by introducing a suitable non-oxidizing gas, but for the purpose of the present invention, a coke oven Fuel gases such as gas, petroleum gas, and mixtures of these gases and low-calorie gases are combusted with an air volume that is 0.4 to 0.7 times the theoretical amount required for complete combustion, and contains almost no oxygen. It is convenient to carry out heating carbonization with hot gas containing unburned fuel gas. As an example, when coke oven scum is used as a fuel gas and the amount of air is 0.5 times the theoretical amount, it is combusted in a non-oxidizing burner. Table 1 shows the results of comparison with the combustion gas composition according to

By operating the internal heating type rotary kiln in a reducing atmosphere in this way, a molded coke with extremely high strength can be obtained. Moreover, the shaped activated coke obtained by activating this shaped coke is
Compared to molded coke with the same porosity obtained by carbonization in an oxidizing atmosphere, it shows a higher activity, perhaps due to a different pore structure, and in addition, it exhibits higher activity than molded coke with the same porosity obtained by carbonization in an oxidizing atmosphere. There is little roughness on the surface of the molded product, which is seen when carbonization is carried out below, and the surface has a smooth and uniform shape.

In addition, if the operation is performed with a large amount of unburned fuel gas remaining, tar and soot will be generated due to cracking of the methane component in the fuel gas, which will adhere to the inner wall of the gas exhaust pipe and cause gas flow to deteriorate. If necessary, a spray device may be installed at the rising end of the gas exhaust pipe to clean the exhaust gas with ammonium water or hot water.

As mentioned above, the main feature of the method of the present invention is that an internally heated rotary kiln is operated in a reducing atmosphere. Since air may get mixed in and the internal gas composition may change, a cover is attached to cover the rotary seal part, and a non-oxidizing gas is injected into the interior at a pressure higher than the internal pressure area of the rotary kill, approximately 500 WAq. Stable operation is possible by using a rotary kiln equipped with a sealing device. In this case, as the non-oxidizing gas for gas sealing, it is most efficient to use the exhaust gas from the rotary kiln or activation furnace in the molded activated coke manufacturing process of the present invention. Further, in the present invention, furnaces other than internal heating type rotary kill/can be used in a reducing atmosphere.

The carbonization conditions may be determined depending on the type of raw material and the performance required by the product, but usually the gas temperature at the gas outlet of the rotary kill is 300 to 500°C, and the temperature in the combustion chamber is 6°C.
A temperature of 00 to 1100°C and a residence time of the product in the rotary kiln of about 0.5 to 1.5 hr are sufficient.

In addition, the combustion exhaust gas when fuel gas is combusted with an air amount 0.4 to 0.7 times the theoretical amount still has a considerable amount of heat generation i as shown in Table 1, so it is effective in other devices. It is possible to use it, and if it is mixed with the fuel gas of the process of the present invention, the economic efficiency of the process of the present invention can be further improved.

Molded coke obtained by carbonizing the molded raw material mixture is activated with steam to produce molded activated coke.

Various types of activation furnaces are used for the activation or regeneration of ordinary activated carbon, but for the purposes of the present invention, a vertical multi-stage bed furnace is used to ensure uniform activation without deforming the product. The method of the present invention uses an easy-to-operate rotary kiln, maintains the high thermal efficiency and porosity that are the characteristics of internal heating, and has high strength. It is possible to continuously produce high-performance molded activated coke with a good yield without dulling the shape.

EXAMPLES The method of the present invention will be specifically explained in Examples below.

Note that the Loga index, strength, specific surface area, desulfurization rate, and denitrification rate shown in Examples were measured as follows.

[Loga index]

The loga index was measured according to the 10 loga test method of JIS M 8801.

〔Strength〕

The strength of the molded product and molded activated coke was measured using the drum tester used for the loga index measurement, and the strength of the molded product and molded activated coke was measured using a sample 2U1 with a particle size of 6 or more.
After charging i' into a drum and rotating the drum 1000 times at a speed of 5 Orpm, the contents are sieved through six sieves and the weight on the sieve is measured [specific surface area] using carbon dioxide gas. It was measured by the Bed method.

[Desulfurization rate, denitrification rate]

The exhaust gas shown in Table 2 was transferred to an absorption device filled with 200i of formed activated coke at an exhaust gas temperature of 150°C and an exhaust gas feed rate of S.
V 50Uhr-1 and So at the absorber outlet
, , The NOx concentration was measured, and the desulfurization rate and denitrification rate were determined using the following equations.

Examples 1 to 6 of NOx concentration in absorption device The main raw material is semi-formed coke obtained by low-temperature carbonization of 1.5% total sulfur, 6Σ button index) in a fluidized carbonization furnace at a carbonization temperature of 460℃ to 500℃. Pitch is added to adjust the loga index of the molding raw material, and after heating and mixing the molding raw material with steam, it is machined into a molding machine v10.
It was made into a tablet-type molded product with f×15 to 20 (mm).

This molded product is supplied to a rotary kiln at 20 to 4 QKv/hr, and the combustion chamber temperature is 800 to 800 in an internal heat reducing atmosphere.
Molded coke was produced by carbonization at 1050° C. for approximately 40 minutes. Next, the amount of steam blown per 20Kf of molded coke is 23.
O~23.5 Kg/hr, furnace temperature 900~92
Molded activated coke was produced by activation in a vertical multistage bed furnace at 0°C for 0.75 to 0.83 hours, and the specific surface area, strength, desulfurization rate,
1. Denitrification rate etc. were measured. The results are shown in Table 3.

In addition, the properties of foreign-made commercially available molded activated coke were also tested and are also listed in Table 3.

Comparative Example A molding material with the same blending ratio as in Example 6 was molded in an internally heated oxidizing atmosphere using a molded rotary kiln (under saddle).
Molded coke was produced by carbonization using a conventional method, which was then activated in a vertical multi-stage bed furnace to produce a molded activated coke product. The yield, strength, specific surface area, desulfurization rate, and denitrification rate of the product (molded coke and shaped activated coke) with respect to the raw material (molded coal) due to the difference between the product and the carbonization method in Example 6 (internal heating under reducing atmosphere) A comparison was made.

The results are shown in Table 4.

The carbonization conditions are as follows.

Air ratio Furnace temperature (in combustion chamber) °C Internal thermal oxidizing atmosphere 1.3 1150 Internal thermal reducing atmosphere 0.5 950 or more Table 4
As can be seen, the product yield V of the active coke produced by the present invention is higher than that produced by internal heating under an oxidizing atmosphere (conventional method), and although the specific surface area is small, it is superior in strength and denitrification rate. It is clear that it was made by

Patent applicant: Mitsui Mining Co., Ltd.

Claims (1)

[Claims] 1. A mixture of semi-formed coke produced from coal as the main raw material, coal and a binder is molded, and the molded product is heated in a reducing atmosphere using an internally heated rotary kill machine. 1. A method for producing shaped activated coke for desulfurization and denitrification, which comprises carbonizing the coke and then activating it. 2. A spray device is attached to the rising part of the gas exhaust pipe of an internally heated rotary kill/, and the exhaust gas is washed with water or ammonium water, etc., and carbonization is performed while preventing the precipitation and adhesion of tar, carbon, etc. The manufacturing method according to item 1. 3. Using fuel gas as the heating source of the internal heating type rotary kill/burning using a smaller amount of air than the theoretical value,
3. The manufacturing method according to claim 1, wherein an internal heating rotary kiln is heated with combustion gas containing unburned fuel gas. 4. Internal heat type rotary kill/ll- with non-oxidizing gas pressurized into the sealing part of the rotating part and equipped with a gas sealing device.
The manufacturing method according to any one of claims 1, 2, and 3. 5. The manufacturing method according to any one of claims 1, 2XA, 3, and 4, wherein the carbonization product is activated using a vertical multistage bed furnace.