RU2769520C1 - Method for producing activated carbon powder - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method for producing activated carbon powder from coal-tar raw materials by exposing to ferromagnetic elements in a rotating electromagnetic field of a vortex electromagnetic apparatus, including loading, crushing, activating by water vapour at high temperature, and unloading, wherein the water is supplied directly into the active area of the apparatus, wherein crushing and activation occur when the ferromagnetic activating elements collide with the coal-tar raw materials—anthracite chips and water vapour at a temperature of more than 250°C, formed by converting the kinetic energy of the moving elements into thermal energy, and the finished products are unloaded by an adjusted air flow carrying fractions of the required granulometric composition from the active area.

EFFECT: production of activated carbon powder from coal-tar raw materials.

1 cl, 1 dwg, 2 tbl, 1 ex

Description

The invention relates to the field of technology for the production of adsorbents, in particular, to methods for producing activated carbon powders based on coal raw materials, which can be used as an adsorbent in the preparation of water for municipal and industrial water supply.

Various technologies for obtaining adsorbents are known, for example, by changing the structure and state of the surface of the adsorbent by chemical modification (Tarkovskaya, I.A. Oxidized coal. Kyiv: Naukova Dumka, 1981 - 200 p.), using solutions of mineral acids, organic reagents, etc. etc., or (and in combination) with mechanical activation in a VM-4 roller-ring vibrating mill, electromagnetic grinder (EMR), ETA-12 mixer and MPW-324 homogenizer (Mechanochemical modification of carbon ad sorbent for purification of phosphoricacid / I.G. Pukhov , N.N. Smirnov, A.P. Ilyin // Abstractof III international conference "Fundamental Bases of Mechanochemical Technologies" - Novosibirsk, May 27-30, 2009 - P. 216, Activation of carbon materials by liquid and gas media under intense mechanical impacts / I.G. Pukhov, S.D. Dmitriev, N.N. Smirnov // Theses of reports - Suzdal, June 29 - July 2, 2010 - P. 68). In this case, in the process of modification, not only the parameters of the porous structure change, but also the physicochemical properties of the surface.

The disadvantages of the considered methods are the high cost of the modifying agent, the duration, multi-stage and laboriousness of the modification process, as well as the high energy intensity of the production processes.

A known method for producing modified active carbon (MAC), including the impregnation of coals with water or hydrochloric acid solution with a concentration of 1÷4 wt. % at a ratio of the total pore volume of coal and water or acid 1.0 ÷ (0.7 ÷ 1.0), and then the treatment of coal with a 9 ÷ 15% solution of thermosetting resin in furfural at a weight ratio of coal and solution 1.0 ÷ (0 ,35÷0.68), keeping to flowability and heat treatment at a temperature rise rate of 450÷900°С/hour to 700÷900°С and subsequent exposure at this temperature for 0.2÷0.5 h (RU patent No. 2175885).

The disadvantage of this method is the high cost of the modifying agent, the duration and complexity of the modification process, as well as the impossibility of implementing this method directly at the water treatment plant.

A known method for producing active anthracite by direct activation of crushed anthracite without a carbonization stage, steam in a moving bed reactor with gas burners (Kinle X. Active coals. - L.: Chemistry, 1984, p. 39).

The disadvantages of this method include the fact that during the interaction of anthracite with water vapor, despite the fact that the volume of micropores increases, anthracite does not have a sufficient level of adsorption properties.

A known method for producing active carbon based on semi-coke of long-flame coal grade "D", including crushing pieces, sowing a fraction of 0.5 ÷ 2.8 mm, drying the grains at 140 ÷ 180 C for 40 ÷ 60 min. and their activation at a temperature of 900÷1000 C with a mixture of water vapor and flue gases to a ratio of micro- and mesopore volumes equal to 1:(1.0÷1.1). (patent RU No. 2164217).

The disadvantages of this method is the low strength of the resulting activated carbon 60÷65% and high energy consumption of production.

Known apparatus of the vortex layer of continuous action (patent RU No. 2613517), with which you can get the powder of activated carbon (PAH). The device works as follows. A reaction chamber is installed in the inductor tube, in the working zone of which there is an insert with ferromagnetic particles rotating in an electromagnetic field. When the device is turned on, voltage is applied to the windings, the process of loading and processing the source material with ferromagnetic particles takes place. The finished product is sent for further processing or to the consumer.

The disadvantage of the method implemented in this device is limited technological capabilities, namely, the inability to control the fractional composition of the obtained PAH and the introduction of additional reagents that provide the required level of sorbent activation.

The technical objective of the invention is to create a continuous energy-efficient method for the manufacture of activated carbon powder (sorbent) from coal raw materials in the required quality and quantity for water purification directly at the water treatment station for municipal and industrial water supply.

To achieve this technical result, a method is proposed for obtaining activated carbon powder from coal raw materials by the action of ferromagnetic elements in a rotating electromagnetic field of a vortex electromagnetic apparatus. The method includes loading, grinding, steam activation and unloading. In this case, water is supplied directly to the active zone of the apparatus, where grinding and activation occur when ferromagnetic activating elements collide with coal raw materials and water vapor at a temperature of more than 250 ° C, which is formed due to the conversion of the kinetic energy of moving elements into thermal energy. The unloading of the finished product is carried out by a controlled air flow, which carries away the fractions of the required granulometric composition from the core.

The novelty and essence of the method lies in the fact that the process is carried out in the reactor core of a vortex electromagnetic apparatus, at temperatures obtained as a result of the conversion of the kinetic energy of the collisions of particles of processed coal with ferromagnetic activating elements into thermal energy. In this case, the background temperature in the reactor reaches 250÷300°C, and at the collision points the instantaneous temperature can exceed 800°C. The water supplied to the reactor core plays the role of not only an activating agent, but also serves to moisten the PAH mass entrained through the ejector into the water treatment process, which subsequently reduces the pulp preparation time.

The technical result of the proposed method consists in creating a continuous energy-efficient method for manufacturing activated carbon powder (sorbent) from coal raw materials of the required quality in the quantities required at the moment directly on the territory of the water treatment plant and feeding it into the technological process of water purification for municipal and industrial water supply. The technical characteristics of the sorbent and the water quality indicators obtained as a result of the experiment confirm the advantage of the proposed method. A significant reduction in energy consumption is achieved through the use of thermal energy obtained as a result of the conversion of the kinetic energy of moving elements into thermal energy, and the continuity of the process is ensured by the features of the proposed design of the vortex electromagnetic apparatus, which allows the supply of water and air to the core, and unloading the finished product with a controlled air flow (PAH) of technologically determined granulometric composition.

The proposed method is illustrated by the drawing (Fig. 1) and Tables 1, 2.

Fig. 1 - Scheme of the installation for the production of activated carbon powder, where 1 - silo; 2 - filter; 3 - level sensor; 4 - vibroaeration system; 5 - butterfly valve; 6 - feedstock; 7 - screw feeder; 8 - download channel; 9 - reactor core; 10 - a glass of non-magnetic material in the working casing; 11 - ferromagnetic elements; 12 - inductor coils; 13 - water supply network; 14 - water flow regulator; 15 - water supply valve; 16 - pipe; 17 - source of compressed air; 18 - air flow regulator; 19 - air supply valve; 20 - air supply hole; 21 - air flow; 22 - output PAH fraction; 23 - ejector; 24 - source of compressed air in the ejector.

Table 1 - Particle size distribution of the obtained PAH.

Table 2 - Technical characteristics of PAHs.

The proposed method is carried out using a specially designed installation - a vortex electromagnetic apparatus (VEG). The technological process is as follows. From the silo, the raw material continuously with a given intensity with the help of a screw feeder enters through the loading channel into the reactor core, which is a glass of non-magnetic material, located in the working casing of an electromagnetic multi-pole (usually 6-pole, 3-phase) inductor, which creates rotating (vortex) field. The vortex electromagnetic apparatus (VEA) is designed for grinding, heat treatment and mechanical activation of coal by agitators - ferromagnetic elements (rods) in an alternating electromagnetic field created in the reactor core by inductor coils. Ferromagnetic rods, randomly rotating in an electromagnetic field, collide with each other and with the crushed material, releasing large thermal energy upon impact. The average temperature in the reactor core is 250÷300°C, and at the impact points it can reach an instantaneous temperature of over 800°C. In the process of grinding, water is supplied through the loading channel, which, when it enters the reactor core, evaporates and intensifies the process of activation of coal particles. During the processing of raw materials in the reactor core, an air flow enters from the compressed air source through the air inlet at the bottom of the reactor cup, which carries the PAH fraction 20–50 μm in size into the suction zone of the ejector located in the upper part of the working casing. The flow of the PAH fraction, entrained by air along the casing in the zones adjacent to the loading channel, located above the reactor core, is saturated with water vapor. The ratio of the amount of water to the amount of feedstock entering the reactor is 0.2÷0.5 l per 1 kg of feedstock. Then, from the ejector, the moistened PAH is fed into the pulp preparation tank, i.e. directly into the water treatment process.

An example of the implementation of the method. The method is carried out using a specially designed installation - a vortex electromagnetic apparatus (Fig. 1). In the silo 1, equipped with a filter 2, through which air is discharged and cleaned when loaded with feedstock, level sensors 3, a vibroaeration system 4 and a butterfly valve 5, feedstock 6 (anthracite chips with a grain size of 2÷5 mm) is located. From the silo, the raw material continuously with a given intensity (1 kg/min) with the help of a screw feeder 7 flows through the loading channel 8 into the reactor core 9, which is a glass of non-magnetic material located in the working casing 10 of the VEA. The vortex electromagnetic apparatus is designed for grinding, heat treatment and mechanical activation of coal by agitators - ferromagnetic elements (rods) 11 in an alternating electromagnetic field with a strength of 0.12 ÷ 0.15 T, created in the reactor core by inductor coils 12. Ferromagnetic rods made of tool steel with a diameter of 2 mm to 4 mm and a length of 20 mm to 40 mm (the ratio of the diameter of the rod to the diameter of the reactor should be in the range of 0.2 ÷ 0.25), weighing 0.2 ÷ 0.35 kg / liter of the working zone of the reactor, randomly rotating in an electromagnetic field with a frequency of 50 Hz, collide with each other and the crushed material, while releasing large thermal energy. The average temperature in the reactor core is 250÷300°C, and at the impact points it can reach an instantaneous temperature above 800°C. In the process of grinding, water is supplied to the reactor core from the water supply network 13 through the water flow regulator 14, the water supply valve 15 through the pipe 16 into the loading channel 8, which, when it enters the reactor core, evaporates with the formation of a steam-air mixture with a humidity of at least 35% and intensifies the process of activation of raw coal.

During the processing of raw materials in the reactor core, from the compressed air source 17 through the air flow regulator 18, the air supply valve 19 and the hole in the bottom of the reactor cup 20, an air flow 21 enters at a speed of 50 l/min, which carries out the output PAH fraction (size 20 ÷ 50 μm) 22 into the suction zone of the ejector 23, located in the upper part of the working casing of the VEG. The ejector is supplied with a compressed air stream from source 24. The PAH fraction stream entrained by air along the casing in the zones adjacent to the loading channel, located above the reactor core, is saturated with water vapor. The ratio of the amount of water to the amount of feedstock entering the reactor is 0.2÷0.5 l per 1 kg of feedstock. Humidified PAH from the ejector is fed directly into the pulp preparation tank.

The feasibility of using the proposed method directly at the water treatment plant for municipal and industrial water supply is confirmed by the experimental results given below. To obtain PAHs, anthracite chips with a grain size of 2–5 mm were used, costing 17 rubles/kg. The particle size distribution of the obtained PAH with an air flow of 50 l/min from a compressed air source at normal atmospheric pressure is presented in Table. 1. Technical characteristics of the obtained activated carbon powder (sorbent) and water quality indicators are presented in Table. 2, while the phenolic number of the obtained PAH was 22±1 mg/l. The method is implemented using a specially designed unit (WEG) with a capacity of 1500 kg/day and a power consumption of 9.5 kW/h, which ensures the continuity of the process due to the design features that allow water and air to be supplied to the core and PAHs to be unloaded with a controlled air flow. The energy consumption for the production of 1 kg of PAHs was 9.5×24/1500=0.152 kWh/kg, which, at an electricity price of ~5 rubles×kWh, amounted to 0.76 rubles/kg for PAHs. Thus, direct costs for the production of PAHs from coal chips, taking into account the costs of compressed air and equipment maintenance, amount to 21 rubles/kg, while the market value of activated mineral carbons starts from 50 thousand rubles. per ton. At the same time, it should be taken into account that their fractional composition does not correspond to the optimal one and there is a problem of explosion safety due to dusting during transshipment at water treatment plants, which more than doubles the economic efficiency of obtaining the sorbent. An alternative could be a sorbent based on charcoal, but its average price in 2020 was 150,000 rubles/ton.

METHOD FOR PRODUCING POWDER OF ACTIVATED CARBON

Claims (1)

A method for producing activated carbon powder from coal raw materials by exposure to ferromagnetic elements in a rotating electromagnetic field of a vortex electromagnetic apparatus, including loading, grinding, activation with water vapor at high temperature and unloading, characterized in that water is supplied directly to the active zone of the apparatus, where grinding takes place and activation upon collision of ferromagnetic activating elements with coal raw materials - anthracite chips and water vapor at a temperature of more than 250 ° C, which is formed due to the conversion of the kinetic energy of moving elements into thermal energy, and the finished product is unloaded by a controlled air flow, which removes fractions of the required granulometric composition from the active zones.

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