RU2341453C2 - Method of activated carbon production and related device for implementation thereof (versions) - Google Patents

Abstract

FIELD: heating; chemistry.

SUBSTANCE: dried carbon-bearing raw material is compressed with following pre-pyrolysis preparation at temperature 300-400°C and removal of released liquid fraction. Thereafter raw material is pyrolysed at 650-700°C. Produced carbon is activated and cooled. Two offered versions of related device for method implementation contains at least two delivery modules, each of which contains in plane drying cabinet with screw pin and heat conductor, and connected pre-pyrolysis and compression chamber with heat conductor. There is also pyrolysis chamber with heat conductor and connected cooling air duct and in-built gas heat-generator, and processing unit from two connected chambers one of which contains dry steam tube activator, and another is covered with water cooling tank.

EFFECT: higher yield and quality of activated carbon.

7 cl, 4 dwg, 1 tbl

Description

The invention relates to the thermal processing of carbon-containing wood raw materials to produce activated carbon and other by-products.

A known method of producing activated carbon, in which the installed volume of carbon-containing raw materials is dried, subjected to pyrolysis in the heated volume of the chamber, after which the coal is activated and cooled (RF patent No. 2100401, С10В 49/02, 31/08, 1995).

This method is implemented in a device containing a heat generator with nozzles connected through a fuel line, as well as a drying chamber, a pyrolysis chamber with a pyrolysis line, and activation and cooling chambers with gates (RF patent for IZ No. 2100401, С10В 49/02, 31/08, 1995).

The disadvantage of the method and the device that implements it is the lack of pre-pyrolysis of the raw material, affecting the quality and yield of the resulting product.

The closest is the method of producing activated carbon, in which the pre-pyrolysis processing of carbon-containing wood raw materials is carried out by drying and pressing, the processed raw materials are subjected to pyrolysis at a temperature of 650-700 ° C, and the obtained hot charcoal is activated and cooled (RF patent for PM No. 37987, СВВ 49/02, 2004).

In the known method, pre-pyrolysis processing by pressing wood raw materials can slightly increase the volumetric content of carbon. However, its disadvantage is the one-stage pyrolysis process at a temperature of 650-700 ° C, resulting in the simultaneous formation of charcoal (carbonizate) with a high carbon content, as well as its necessary heating for the activation process. This leads to the fact that during the pyrolysis, liquid and gaseous fractions are removed, which leads to a significant decrease in the yield of charcoal (about 20%), and therefore, after its activation, and to a low yield of activated carbon.

Another disadvantage is that during the pyrolysis, the liquid fraction formed due to the decomposition of the main components of wood raw materials under the influence of thermal decomposition reactions, with a further increase in temperature to 650-700 ° C, begins to partially evaporate, passing into the pyrolysis gas, and partially precipitate as a precipitate, which clogs its pores, reducing their volume and adsorption activity. And since mineral compounds are dissolved in the liquid fraction, which give ash during pyrolysis, its incomplete removal from the dry residue - charcoal (carbonizate) affects the ash content of activated carbon in terms of the mass fraction of ash.

The technical result of the method is to increase the yield of activated carbon and its quality with an increase in pore volume, adsorption activity and a decrease in the mass fraction of ash.

The technical result of the method is achieved by the fact that in the pre-pyrolysis processing mode after drying, preliminary pyrolysis of wood raw material is carried out at a temperature of 300-400 ° C, during which the liquid fraction is removed from the processed raw material by pressing.

The closest (according to the first embodiment) is an installation containing a receiving-supplying unit connected in series with a pyrolysis chamber containing an annular heat conduit with a gas heat generator connected and located inside it at the outlet of the chamber, made in the form of an annular burner compartment, and with a processing unit made in the form two series-connected chambers, in the first of which there is an activator made in the form of a tube for dry steam, and in the second chamber the cooling unit is made in the form of an annular tank under water, the outer wall of which covers the wall of the chamber, while the receiving-supplying unit contains a feed drive and a drying chamber connected to the compression chamber with a piston, the pyrolysis chamber wall being covered by the outer wall of the annular heat conduit (RF patent for ПМ No. 37987, СВВ 49/02, 2004).

The disadvantage of the installation is the low yield of activated carbon and its quality in terms of pore volume, adsorption activity and ash mass fraction, due to the single-stage pyrolysis at high temperature to obtain not only charcoal, but also its heating to the temperature necessary for activation.

The technical result of the installation is to increase the yield of activated carbon and its quality with increasing pore volume, adsorption activity and a decrease in the mass fraction of ash.

The technical result (according to the first embodiment) is achieved by the fact that the heat pipe of the pyrolysis chamber additionally contains a cooling duct connected to it, and the chambers in the receiving-supply unit additionally contain two annular heat pipes connected to each other, the outer wall of each of which encompasses the corresponding chamber wall, while the drive the feed is made in the form of a screw and is located in the drying chamber, and the transceiving unit is made in the amount of at least two identical blocks, the heat pipes of which are connected to a common for them the heat-conducting pyrolysis chamber.

The closest (in the second embodiment) is an installation containing a receiving-supplying unit connected in series with a pyrolysis chamber containing an annular heat conduit with a gas heat generator connected to it at the outlet of the chamber with a burner compartment, and with a processing unit containing an annular cooling unit and two series-connected chambers with an activator in the first of them, while the transceiving unit contains a feed drive and a drying chamber connected to the compression chamber with a piston, the wall of the pyrolysis chamber being and the outer wall of the annular heat conductor (RF patent for PM №37987, S10V 49/02, 2004).

The disadvantage of the installation is the low yield of activated carbon and its quality in terms of pore volume, adsorption activity and ash mass fraction, due to the single-stage pyrolysis at high temperature to obtain not only charcoal, but also its heating to the temperature necessary for activation.

The technical result of the installation is to increase the yield of activated carbon and its quality with increasing pore volume, adsorption activity and a decrease in the mass fraction of ash.

The technical result (in the second embodiment) is achieved by the fact that two cooling ducts are introduced into the installation, and two chambers of the receiving-supplying unit additionally contain two interconnected annular heat pipes, the outer wall of each of which covers the corresponding chamber wall, the feed drive is made in the form of a screw and located in the drying chamber, while the receiving-supplying unit is made in an amount of at least two identical units, the heat pipes of which are connected to the pyrolysis chamber heat pipe common to them, and the gas heat generator and the first cooling duct are connected to the heat pipe of the pyrolysis chamber from its outer side, and in the processing unit the cooling unit is made in the form of an annular air duct, the outer wall of which covers the wall of the first chamber and is connected to the second duct, and the activator is made in the form of a supply pipe water with holes.

The technical result (according to the second embodiment) is also achieved by the fact that in the gas heat generator the burner compartment is made in the form of an expanding socket connected to the flame tube, covered by a longer insulated pipe with an annular base and an outlet, and an annular gap under the air flow is located between the pipes temperature regulation.

The technical result (according to the second embodiment) is also achieved by the fact that the heat pipe of the pyrolysis chamber is connected to the duct of the first chamber of the processing unit through an additional heat pipe.

The technical result (according to the second embodiment) is also achieved by the fact that the gas heat generator is connected to the heat pipe of the pyrolysis chamber through the side of the additionally introduced annular heat exchanger located in its annular channel and containing a side inlet channel and output channels connected to it.

The technical result (in the second embodiment) is also achieved by the fact that the cooling duct is connected to the heat pipe of the pyrolysis chamber through an additionally introduced ring heat exchanger located in the ring channel of the heat pipe with a gap from its inner wall and containing a lateral inlet channel and an output channel connected to it in the form of an annular grooves.

The method of producing activated carbon is described through the operation of the installation, where Fig. 1 shows a diagram of a first installation option, Figs. 2 and 3 show a general view and a corresponding diagram of a second installation option, and Fig. 4 shows a construction of a gas heat generator, and in the table the comparative characteristics of the obtained activated carbon of the BAU-A brand (GOST 6217-74) from crushed birch are given for different processing options at the claimed installation for the same time - 1 hour (average data for 3-5 tests).

As raw materials, the method uses crushed lignocellulosic and carbon-containing raw materials of plant origin from wood, including waste from woodworking production (branches, rhizomes, wood chips, sawdust, shavings). "Grinding of raw materials is carried out in industrial grinders and sorted to size fractions from 2 × 2 × 2 mm to 20 × 15 × 10 mm."

The installation for producing activated carbon contains at least two receiving and receiving units, each of which has a drying chamber 1 with a screw 2 and a heat conduit 3, a pre-pyrolysis and compression chamber 4 with a heat conduit 5 and a compression piston for raw materials 6, and a pyrolysis chamber 7 with a heat conductor 8 , the duct 9 and the piston 10 of the supply-overlap of the entrance and its opening, as well as the processing unit.

According to the first embodiment, the processing unit is shown in Fig. 1 and contains an activation chamber 11 with a tube 12 for supplying dry steam to the chamber, as well as a cooling chamber 13 with a capacity of 14 under water.

In a second embodiment, the processing unit is shown in FIGS. 2-3 and comprises a first chamber 15 with an annular air duct 16 to which a cooling duct 17 is connected, with an activator in the form of a tube 18 with holes for supplying water from the water system 19, and a second chamber 20 .

The gas heat generator 21 according to the first embodiment and when it is located inside the heat pipe of the pyrolysis chamber is made in the form of an annular burner compartment (not shown) with the corresponding elements ensuring its operation — gas (propane and pyrolysis) nozzles, igniters and air channels.

The gas heat generator 21 according to the second embodiment, and when it is located and connected externally to the heat pipe to its side, is structurally made in accordance with FIG. 4 and comprises a burner 22 with a gas (pyrolysis) nozzle, an igniter 23 with one or more gas (propane) nozzles, a swirl 24 stream of generated hot gas, the burner compartment, made in the form of an expanding bell 25, insulated pipe 26 with duct 27.

The gas heat generator 21 can be connected to the heat conduit through the inlet side channel of the ring heat exchanger 28, which also contains output channels perpendicular to the side channel in the direction of the pyrolysis chamber inlet, located at different angles in its axial direction to swirl and ensure uniform distribution of the heat flux in the heat conductor.

The damper 29 is designed to overlap adjacent chambers 7 and 15, the fan 30 is designed to create an air flow, the first duct 9 of which is connected through a heat exchanger 31 to the heat pipe 8 at the inlet of the pyrolysis chamber 7 to change the temperature regime in the heat pipe of the receiving and receiving unit, and its second duct 17 s a throttle valve for the implementation of the feed or shutoff mode is connected to the annular air duct 16 of the first chamber 15 of the processing unit and is additionally connected through a heat exchanger 33 to the heat conduit 32 with a throttle throttle valve (not shown) connected to the heat conduit 8 of the pyrolysis chamber 7. In this case, the throttle valves work to implement cooling or heating chamber 15.

To carry out the combustion process, the heat generator 21 is connected through a duct 27 to a fan 30 and through a burner 22 to a pyrolysis conduit 34 connected through a condenser 36 to the afterburner 37, the piston 38 of the second chamber 20 is designed to supply, overlap and open the cavity of the first chamber 15, and the camera 20 has a lock compartment 39 located between the shutters 40 and 41.

If there are two or more receiving and receiving units in the installation, the technological process implemented in it allows the formation of an increased amount of charcoal at the stage of preliminary pyrolysis without additional energy costs for fuel consumption.

Each of the drying chambers 1 is a cylindrical, vertically mounted container. Drying of the raw materials in the chamber 1 is carried out due to the supply through the heat conduit 3 of the heat generated by the heat generator 21 through a wall common with the chamber. Partially, the coolant enters the drying chamber 1 through an opening in the corresponding chamber of pre-pyrolysis and compression 4. Drying is carried out at a temperature of 180-220 ° C.

The waste coolant through the pipes is discharged through the exhaust pipe into the atmosphere. To intensify the drying of the raw materials in the chamber is mixed with a screw 2, located in its central part. When unloading raw materials into the chamber of pre-pyrolysis and compression 4, the screw rotates in the opposite direction. The main purpose of the screw 2 is the movement of raw materials, with the help of which it can pass all the chambers in the position of the pistons and valves “open”. To reduce heat loss, the drying chamber contains an outer layer of thermal insulation. In the lower part, the cylindrical profile of the chamber becomes conical and ends with a flange with a hole. The flange is designed to connect the drying chamber to the pre-pyrolysis and compression chamber 4.

In the case of the installation with two receiving and receiving units, the pre-pyrolysis and compression chambers 4 in a particular case can occupy a position on one common diametrical axis passing through their axis of symmetry and can be made in the form of cylindrical containers, as shown in Figs. 1-3.

A slight movement, and consequently, compression of the raw materials in each of the chambers 4 is carried out by a corresponding piston 6 connected to a drive mechanism (not shown). The dried raw material entering the chamber 4 is in a temperature medium without air access, in which the wood raw material is decomposed into liquid and gaseous fractions with their simultaneous removal through the corresponding openings in the chamber. In this case, the liquid fraction in the composition of the raw material is removed by pressing, leaving a solid residue in the chamber in the form of charcoal.

Pressing allows, by compressing such raw materials (using a piston in chamber 4), to isolate the liquid fraction and squeeze it out through drainage holes (not shown), thereby removing it.

The temperature in the chamber 4 is created by heating its wall with heat using a heat carrier, which is blown through the annular channel of the surrounding heat conduit 5. The heat carrier has a temperature obtained by mixing in the heat exchanger 31 hot air coming in through the heat conduit 8 of the pyrolysis chamber 7 with air coming in through the duct 9 from the fan 30 with the possibility of regulating its air flow using a throttle (not shown).

The main components of wood in the form of hemocellulose, cellulose and lignin have decomposition temperatures of 200-260, 240-350 and 250-400 ° C, respectively, and in order to have charcoal with a high carbon content, the temperature at which decomposition is necessary mentioned components. Such a temperature is a temperature in the range of 300-400 ° C. The minimum temperature is due to the beginning of the decomposition of wood, and the maximum is due to its cessation, at which the solid residue begins to sinter, increasing density and turning into charcoal. From the above table it follows that in the indicated temperature range, a technical result is obtained by increasing the yield of activated carbon and improving its quality indicators with an increase in pore volume, adsorption activity and a decrease in the mass fraction of ash.

The heat exchanger 31, to which the cooling duct 9 is connected, is designed to evenly distribute the air flow in the heat conduit and mix the air flow from the fan 30 with the heat flow from the heat generator. It is made circular, located in the circular channel of the heat pipe of the pyrolysis chamber at its inlet and with a gap from the inner wall of its heat pipe, there is a lateral inlet channel for connecting to the cooling duct 9 and an annular outlet channel perpendicular to it in the form of an annular groove at the outlet of which mixing air and hot gas flows to form a predetermined pre-pyrolysis temperature. The compression mode of the raw material occurs when the piston 10 of the pyrolysis chamber 7 is “closed”, when the hole connecting the pyrolysis and pre-pyrolysis chambers is blocked, and the raw material can only reach the piston. In this mode, the raw material during simultaneous operation of the screw of the corresponding drying chamber and the compression piston completely fills the pre-pyrolysis chamber 4 and during intensive operation of the piston is compacted to the state of appearance of a slurry that flows through the holes in the lower part of the chamber. The "dirty" pyrolysis gas formed in the pre-pyrolysis chamber 4 through pyrolysis conduit 35 enters the condenser 36, where it is cleaned of the liquid component, and then enters the afterburner 37 and completely burned.

To organize the annular channel formed by the heat conduit of the corresponding chamber 4, the chamber itself is placed inside a pipe of a larger diameter. To reduce heat dissipation into the environment, thermal insulation is applied to the outer surface of the corresponding heat pipe.

The pre-pyrolysis and compression chambers 4 are connected through the heat exchanger 31 to the pyrolysis chamber 7. At the moment when the process of pre-pyrolysis of the raw material is carried out, the pyrolysis process itself is carried out in the pyrolysis chamber 7.

The final pyrolysis in chamber 7 is intended for heating charcoal (carbonizate) to the temperature of the activation process and occurs when the shutter 29 is closed, separating the chamber 4 from the processing unit, at a temperature of 650-700 ° C created in the heat exchanger 28 by mixing hot gas from gas a heat generator, heated to a temperature of 900 ° C, with air entering through the duct 27.

Heat is supplied to the pyrolysis chamber 7 through the pipe wall, common with the wall of its heat conduit 8, and the heated gas generates a gas heat generator 21. The piston 10 in the pyrolysis chamber 7 serves to block or open the inlet, respectively, during the pyrolysis or when loading raw materials, and, if necessary, can partially fulfill the function of a screw for its advancement.

At the end of the pyrolysis process, the operation mode of the gas heat generator 21 is reduced to a certain level due to a decrease in the pressure of the pyrolysis gas entering the burner 22 from the pyrolysis chamber 7 via the pyrolysis line 34.

After the final pyrolysis at a temperature of 650-700 ° C, the heated charcoal is moved from the pyrolysis chamber 7 with the shutter 29 open to the processing unit for its activation and cooling. In this case, the dried raw material under the action of the screw 2 of the corresponding receiving and receiving unit moves from the drying chamber to the chamber 4, pushing the charcoal (carbonizate) obtained in it, which in turn moves the heated coal from the pyrolysis chamber 7 into the chamber 15 to the piston 38 of the second chamber 20 located in the closed position.

In the case of the processing unit according to the first embodiment of the installation, the coal activation process is carried out in the chamber 11 with the inlet and outlet shutters closed by supplying dry steam through the tube 12.

The end of the process is completed by moving the treated coal into the cooling chamber 13, which is blocked by the piston 38 and the shutter 29. The cooling process is carried out by pumping water into a container 14, covering the wall of the chamber.

In the case of the processing unit according to the second embodiment of the installation, the obtained pre-heated charcoal enters the chamber 15, which is blocked by the shutter 29 and the piston 38. Activation is carried out in the chamber 15 by supplying water under pressure from the water system 19 to spray it using a tube activator 18 with many holes. The steam generated when water droplets get on hot coal rinses the pores of the coal and opens them, activating it. Spraying water allows you to activate and simultaneously accelerate the cooling process of hot coal, increasing the quality and yield of the finished product.

To prevent condensation of steam on the inner wall of the chamber during the activation process and to prevent an increase in humidity of the cooled activated carbon, the first chamber 15 is heated from the outside by gases passing through its heat pipe 16 from the heat exchanger 33, where the hot gas of the heat pipe 32 and the air of the duct 17 are mixed to a certain temperature. The activation process stops at a temperature in the chamber in the range of 150-160 ° C. After that, the water supply to the chamber is stopped and further cooling of the activated carbon begins.

To this end, air is supplied to the heat conduit 16 of the chamber 15 through the duct 17 from the fan 30. In this case, the hot gas from the heat conduit 32 is blocked by a throttle valve. Cold air, passing along and across the chamber, lowers its temperature, cooling the coal, and is released into the atmosphere through an exhaust pipe. Water vapor and gases released during the activation and cooling process enter the condenser 36 and are burned in the afterburner 37, and the combustion products are released into the atmosphere.

The process ends at the end of the process in the pyrolysis chamber with the next portion of charcoal, after which the movement of active (activated) carbon in the chamber 15 begins under its own weight in the second chamber 20 of the processing unit, located obliquely to the first. The coal entering the chamber 20 by means of a piston 38 reaches the shutter 40 and is held therein, after which the shutter 40 is opened and the active carbon enters the lock chamber with the shutter 41, where it is again kept to a temperature of 50 ° C. When the shutter 41 is opened, the finished activated carbon enters directly into the metal container and then is packed in bags.

Table Name of indicator Prototype: pyrolysis at 650-700 ° C without pressing Technical solution: pyrolysis at 650-700 ° C and preliminary pyrolysis without simultaneous pressing at: The claimed solution: pyrolysis at 650-700 ° C and preliminary pyrolysis with simultaneous pressing at: 300 ° C 350 ° C 400 ° C 300 ° C 350 ° C 400 ° C Exit (%) 20.8 22.1 22.1 22.4 23.6 23.8 23.9 Mass of activated carbon (kg) 44 46.8 46.8 47.4 49.9 50.3 50,5 Iodine Adsorption Activity (%) 60.8 62.0 62.0 63.3 68.0 68.0 69.8 The total pore volume in water (cm ³ / g) 1,6 1,6 1,62 1,6 1,66 1.68 1.8 Mass fraction of ash (%) 4.7 3.8 3.27 3.2 0.6 0.51 0.48 Other indicators also comply with GOST 6217-74

Claims (7)

1. The method of producing activated carbon, in which pre-pyrolysis processing of carbon-containing raw materials is carried out by drying and pressing, the processed raw materials are subjected to pyrolysis at a temperature of 650 ° -700 ° C, and the obtained hot charcoal is activated and cooled, characterized in that in the pre-pyrolysis processing mode after drying, preliminary pyrolysis of wood raw material is carried out at a temperature of 300-400 ° C, during which the liquid fraction is removed from the processed raw material by pressing. 2. Installation for producing activated carbon, comprising a receiving-supplying unit connected in series with a pyrolysis chamber containing an annular heat conductor with a gas heat generator connected and located inside it at the outlet of the chamber, made in the form of an annular burner compartment, and with a processing unit made in the form of two in series connected chambers, in the first of which there is an activator made in the form of a tube for dry steam, and in the second chamber the cooling unit is made in the form of an annular container for water, external the wall of which covers the wall of the chamber, while the receiving and receiving unit comprises a feed drive and a drying chamber connected to the compression chamber with a piston, the wall of the pyrolysis chamber being covered by the outer wall of the annular heat conduit, characterized in that the heat conductor of the pyrolysis chamber further comprises a cooling duct connected to it the chambers in the receiving and receiving unit additionally contain two interconnected annular heat pipes, the outer wall of each of which covers the corresponding wall of the chambers s, the feed drive is made in the form of a screw and is located in the drying chamber, and the receiving-supplying unit is made in the amount of at least two identical blocks, the heat pipes of which are connected to the pyrolysis chamber heat pipe common to them. 3. Installation for producing activated carbon, comprising a receiving-supplying unit connected in series with a pyrolysis chamber containing an annular heat conduit with a gas heat generator connected to it at the outlet of the chamber with a burner compartment, and with a processing unit containing an annular cooling unit and two series-connected chambers with an activator in the first of them, while the transceiving unit contains a feed drive and a drying chamber connected to the compression chamber with a piston, and the wall of the pyrolysis chamber is surrounded by an external wall th annular heat conduit, characterized in that two cooling ducts are introduced, and two chambers of the receiving-supplying unit are located in one plane and further comprise two interconnected annular heat conduits, the outer wall of each of which covers the corresponding chamber wall, the feed drive is made in the form of a screw and located in the drying chamber, while the receiving and receiving unit is made in the amount of at least two identical units, the heat pipes of which are connected to the pyrolysis chamber heat pipe common to them, etc. than the gas heat generator and the first cooling duct are connected to the heat pipe of the pyrolysis chamber from its outer lateral side, and in the processing unit, the cooling unit is made in the form of an annular air duct, the outer wall of which covers the wall of the first chamber and is connected to the second duct, and the activator is made in the form of a tube for water supply with holes. 4. Installation according to claim 3, characterized in that in the gas heat generator the burner compartment is made in the form of an expanding bell connected to a flame tube covered by a longer insulated pipe with an annular base and an outlet, and an annular gap under the air flow between the pipes temperature regulation. 5. Installation according to claim 3, characterized in that the heat pipe of the pyrolysis chamber is connected to the duct of the first chamber of the processing unit through an additional heat pipe. 6. Installation according to claim 3, characterized in that the gas heat generator is connected to the heat pipe of the pyrolysis chamber through the side of an additionally introduced annular heat exchanger located in its annular channel and containing a side inlet channel and output channels connected to it. 7. Installation according to claim 3, characterized in that the cooling duct is connected to the heat pipe of the pyrolysis chamber through an additionally introduced ring heat exchanger located in the annular channel of the heat pipe with a gap from its inner wall and containing a lateral inlet channel and an output channel connected to it in the form of an annular grooves.

Images