RU2628602C1 - Wood coal production device - Google Patents

Abstract

FIELD: wood industry.

SUBSTANCE: wood coal production device includes the furnace body, provided with thermal insulation, the external combustion chamber, communicating with the pyrolysis chamber, containing the removable wood charging devices, the flue and the exhaust system. The working space of the furnace is made in the form of the loop channel, equipped with the heat-resistant fan, the rotary gate valve and the gas-permeable recuperator, installed inside the looped channel. The gas-permeable recuperator is made of heat-resistant bricks. The weight of the heat-resistant brick for the gas-permeable recuperator is not less than ten times more of the wood to be pyrolyzed. The furnace body is provided with the door for horizontal loading-unloading of the removable devices, before which the rotary gate valve is installed, and each removable device is made in the form of the vertical pillar, evenly provided with the fixing rods along the entire length pointing upwards and fixed at the angle to the vertical pillar. The fan is preferably installed behind the pyrolysis area along the gas flow path.

EFFECT: production of the high quality wood coal both in terms of calorific value and homogeneity and mechanical strength, with the significant reduction in pyrolysis time, increased productivity and energy efficiency, the device is characterized by constructive simplicity and low capital costs.

6 cl, 4 dwg

Description

The invention relates to the field of producing coal from wood and its waste by the pyrolysis method and relates to the construction of a charcoal burning device.

The present invention can be used, preferably, for peregulivaniya wood fuel briquettes (for example, "Eurodrova"), formed from pre-chopped and dried wood, including all types of waste logging and industrial processing of wood.

In the existing charcoal practice, as a rule, wood is placed in a heating furnace in loading tanks, for example, a retort type. The heat from the walls of the retort through the gas layer is transferred to the wood by radiant heat flow and convection.

The greatest practical distribution was gained by circulation furnaces. The principal constructive solution of the circulation furnace is described, for example, in copyright certificate No. 779782 “Circulation furnace” (F27B 9/32, July 26, July 78): in the furnace body, the working chamber is separated from the circulation gas channel in which the heaters and one or more fans.

Modern industrial furnaces of complex wood processing are structurally complex and are focused on the isolation of all types of thermal decomposition products: charcoal, acetic acid, birch tar, soluble and insoluble acids, liquid combustible substances of higher calorific value, etc. A similar furnace is described in patent RU No. 2582696 "Installation for the production of charcoal" (С10В 1/04, priority: 12/29/2014).

Currently, liquid pyrolysis products obtained in the production of charcoal are not in demand, therefore, it is more efficient to burn them, reducing the coolant consumption for the pyrolysis process.

In this regard, plants for integrated wood processing, such as in the above patent RU No. 2582696, are of limited use and are not of interest for industries aimed at obtaining the only target product - charcoal.

In the process of patent search, a wide variety of charcoal burning devices have been identified, which are intended, preferably, to work in close proximity to a source of raw materials, that is, in a timber industry farm, a logging station or at a woodworking enterprise. At such enterprises, it is not economically feasible to trap and process liquid pyrolysis products; therefore, stoves are used that are oriented to obtain one commercial product - charcoal. It is desirable that such devices do not need additional sources of fuel after reaching the specified technological mode.

Such devices include the well-known “Device for producing charcoal” according to patent RU No. 2115689 (С10В 53/02, СВВ 1/04; priority - January 24, 1997), including a furnace with a furnace, air ducts, chimneys and heated chambers with openings in which removable retorts are installed. According to the invention, the lower part of the retort is made in the form of a grate, open to the heated chamber. The heated chamber has at least three holes for retort installation. Ducts and chimneys are equipped with gates. The furnace furnace is installed outside the heated chamber and connected to it by gas ducts. The walls of adjacent heated chambers form the walls of the furnace. In the wall between the heated chamber and the furnace, the main gas duct is made in the upper part of the furnace and the auxiliary gas duct in the lower part of the furnace for ignition of combustible combined-cycle gases in the chamber, which are burned in the chamber in close proximity to the retorts.

Known designs of pyrolyzers for the production of charcoal, which provide for the collection and evacuation of combustible gas and vapor to an additional burner device. For example, SU patent No. 1826983 “Pyrolyzer” (С10В 1/04, 53/02; priority - 05.27.91). The pyrolyzer contains an outer casing with a lid, an inner casing with a ceiling, a firebox with a grate and a burner, moreover, windows are made in the ceiling, below which are retorts with lids, under which there is a burner with a furnace, and the lid of the outer casing on the ceiling side it has a heat-resistant seal and is placed with a gap with respect to the ceiling, while the cavity formed between them is connected by a pipeline to the burner device m Firewood is loaded into the furnace only to start the pyrolyzer.

The closest analogue in technical essence, the presence of similar features and the achieved result is “Device for producing coal” according to patent RU No. 2237699 (СВВ 53/02, priority - 08.07.2003). The device includes a firebox communicating with a pyrolysis chamber containing cylindrical retorts arranged in rows, while gas flow guiding elements are installed in the pyrolysis chamber between the arch and the hearth, which are vertical columns having concave cylindrical surfaces facing the outer cylindrical surfaces of the retorts and located equidistantly in relation to them, which allows to increase the uniformity of heating of the retorts and thereby increase the efficiency of the device due to the intensification tion of the pyrolysis process.

In order to further analyze the prototype and the alleged invention, we highlight the following features of the prototype:

- the furnace is launched by burning any type of fuel in the furnace to produce flue gases at the inlet to the pyrolysis chamber with a temperature of 600 ÷ 650 ° C;

- when the furnace reaches a stable operating mode, further pyrolysis is carried out due to the heat from the combustion of the wood thermal decomposition products, and in subsequent retort loading times, the pyrolysis is due to the heat from the combustion of the pyrolysis wood gases preceding the loading of the retorts;

- heat transfer to the wood material is carried out through the wall of the retort by radiant heat flow and convection;

- the complete kinetic cycle of gas flows in the installation consists of the following successive stages: the formation of steam and gas in the retort during the pyrolysis process - advancement through the gas duct system to the furnace - combustion in the furnace - advancement of the combustion products of steam and gas through the pyrolysis chamber - discharge into the atmosphere through the gas exhaust system. The gas stream performs only one full cycle described above;

- the set of chamber retorts, in which the pyrolysis process proceeds with a time lag depending on the order of loading, and the vertical guide columns installed in the chamber, is a kind of recuperator that ensures the stability of the temperature regime inside the pyrolysis chamber;

- loading and unloading of individual retorts is carried out vertically with a time lag in a working furnace;

- for collecting, forming and delivering the flows of pyrolysis products into the furnace, a gas duct system has been implemented;

- combined cycle gases burn in the firebox;

- maintaining the required temperature is ensured by an adjustable intake of outside air;

- after passing the combustion products of combined cycle gases through the pyrolysis chamber, they are sent to the gas removal system.

Significant disadvantages of this installation for coal should include the following:

- the complexity of the pyrolysis chamber device;

- the complexity and insecurity of sequential loading and unloading of individual retorts;

- significant heat loss due to loading and unloading of each retort separately;

- the ability to change the geometry and spatial location of the guides of the vertical columns during continuous operation of the furnace in load-unload mode;

- the difficulty of controlling the end of pyrolysis in each individual retort under conditions of their sequential periodic loading with a time lag;

- non-uniformity of wood charring within each individual retort;

- inefficient gas venting in the absence of artificial traction, on the one hand, and significant occupancy of the pyrolysis chamber, on the other hand;

- the need to monitor the state of the grate retort system.

The technical task of the invention is the creation of an effective industrial installation with a capacity of at least 0.3 t / h. for charcoal, operating continuously on the heat of the exothermic reaction of thermal decomposition of wood and allowing to obtain high-quality homogeneous charcoal.

The technical result achieved by using the proposed installation is as follows:

- productivity increase;

- structural simplicity of the furnace;

- low capital costs;

- reduction in operating costs;

- high energy efficiency;

- obtaining high quality charcoal, both in calorific value, and in uniformity and mechanical strength;

- a significant reduction in the time of pyrolysis of wood with its approach to a thermodynamic optimum;

- improvement of working conditions and safety measures;

- reduction of environmental risks during operation of the furnace.

The technical result is achieved by the fact that in the installation for producing charcoal, including a furnace body equipped with thermal insulation, an external firebox communicating with a pyrolysis chamber containing removable devices for loading wood, a gas duct system and an exhaust gas exhaust system, the working space of the furnace is made in the form of a loopback a channel equipped with a heat-resistant fan, a rotary gate and a gas-permeable recuperator installed inside the looped channel, while a gas-permeable recuperator It executes the heat-resistant bricks. Moreover, in the installation, the mass of heat-resistant brick to perform a gas-permeable recuperator is not less than ten times the mass of wood loaded for pyrolysis; the furnace body is equipped with a door for horizontal loading and unloading of extraction devices, in front of which a rotary gate is mounted, and each extraction device is made in the form of a vertical strut, evenly provided with fixing rods directed upward and fixed at an angle to the vertical strut over the entire height. In addition, the fan is preferably installed downstream of the pyrolysis zone along the gas stream.

The technical essence of the proposed solution is as follows.

1. The heat capacity of wood is the sum of the heat capacity of the wood itself and the heat capacity of the moisture contained in it, as well as resinous substances. In this case, the heat capacity of resinous substances is 1.5 times, and water is 2.5 times more than the specific heat of absolutely dry wood, which is ≈1.55 kJ / (kg-K) at a temperature of 0 ° C.

It is known that the total humidity of freshly cut coniferous wood is 45 ÷ 50%, soft-leaved - 40 ÷ 50%, hard-leaved - 30 ÷ 45%. Hence, a significant content of water vapor in the gas-vapor pyrolysis steam-gases without its preliminary preparation. In the case of overburdening of wood briquettes formed from pre-crushed and dried to a moisture content of less than 5% wood material, the moisture content in the pyrolysis furnace is several times lower and, accordingly, much less heat is required for the pyrolysis of such material.

If in the prototype the pyrolysis process is implemented at a gas temperature in the pyrolysis chamber of 600 ÷ 650 ° C, then in the proposed device it is sufficient to maintain the temperature of the gas coolant in the range of 400 ÷ 450 ° C.

2. The charring of wood briquettes is carried out in a dynamic flow of gas coolant, and the turbulence of the gas flow in the pyrolysis zone is very significant and is estimated at not less than 5000 Reynolds number.

Immediately each briquette in the proposed solution is washed by a gas coolant under conditions of equal contact of the briquettes with a powerful turbulent gas flow. It is high gas turbulence that ensures uniform heat distribution in the pyrolysis zone.

In the prototype, the movement of the gas stream is closer to the laminar one, which does not help to equalize the temperature regime in individual zones of the pyrolysis chamber. In addition, the presence of guide vertical columns in the pyrolysis chamber worsens the dynamics of the advancement of the gas stream as a whole.

3. The residence time of wood briquettes in the proposed furnace is reduced to 2 ÷ 3 hours: firstly, as noted above, due to the low moisture content in the original pressed crushed material, and, secondly, due to the direct contact of each briquette with a turbulent gas coolant. Under these conditions, the process of heat transfer to wood is greatly simplified: the only thermal resistance in this case is a gas film near the surface of a piece of wood. Also, the pyrolysis process in the proposed solution is significantly intensified due to the rapid removal of thermal decomposition products from the wood surface.

In the prototype, as noted above, heat transfer to the wood material is effected through the retort wall by radiant heat flux and convection, and the pyrolysis products are removed less intensely.

4. In the proposed solution, it is preferable to send wood briquettes to the pyrolysis, preferably with a through hole in the center. This form of briquettes removes the issue of unevenness of the carbonization in the volume when the pyrolysis in the central part is less intensive and when it is necessary to increase the carbonization time to ensure complete pyrolysis of the central part. As a result, the quality of coal on the surface of the wood briquette decreases due to an increase in the content of more inert carbon with a structure close to graphite.

Also, the presence of a through hole in the center of the briquette provides more intensive cooling of the briquettes after unloading from the furnace.

From a structural point of view, the recommended form of the briquette provides a reliable fixation of each briquette on the boot extraction device.

In the prototype, the problem of heterogeneity of the obtained charcoal is not solved.

5. In the proposed solution, the output of charcoal is 320-380 kg of 1 ton of briquettes. The productivity of the furnace can vary in a wide range depending on the task.

A comparative analysis of the proposed technical solution and the prototype solution shows that a new set of known and unknown features claimed in the claims made it possible to realize the above technical problem: a high-performance energy-efficient industrial unit was created that operates continuously on the heat of the exothermic reaction of wood thermal decomposition and allows to obtain high quality homogeneous charcoal.

The fundamental difference between the proposed installation and the prototype is a constructive solution of the furnace working space, namely: the creation of a working space in the form of a looped channel with the organization of a powerful turbulent flow of gas coolant passing through the channel in the mode of repeating cycles.

It is also necessary to note a fundamentally different approach in the proposed solution and in the prototype regarding the organization of the kinetics of the gas flow: it is proposed to use a powerful fan installed in the channel to create a dynamic gas flow with a turbulence of at least 5000.

In the proposed invention, the constructive solution of the recuperator, providing a stable temperature regime inside the furnace channel with maximum use of the heat of the exothermic thermal decomposition reaction, as well as the presence of a rotary gate in the working channel, is important in achieving the goal.

The above comparative analysis of the proposed solution and the prototype solution indicates that the proposed solution meets the patentability criterion of "novelty."

However, some distinctive features that characterize the claimed solution, identified in currently known information sources.

1. The use in the working space of the pyrolyzer of a slide gate valve is known in patent RU No. 2120459 “Pyrolyzer for the production of fuel coals” (С10В 1/04, priority - 04/22/1997). In the patent, the drying process of wood material is regulated by means of a slide gate valve installed at the outlet of the chamber, which distributes the amount of hot gases that are used to heat the retort of the kiln drying chamber and to be utilized through the gate valve of the exhaust gas outlet system. The purpose of installing this slide gate valve is to provide fuel coals of various quality.

2. The management of gas flows of the coolant using fans is known from patent RU No. 2433158 "Method and device for the utilization of carbon-containing waste by pyrolysis" (С10В 1/04, priority - 01/18/2010). In the sectional installation according to the patent, the last section is equipped with an exhaust smoke exhauster, and the furnace is equipped with a discharge smoke exhauster for supplying fuel gases to the gas supply line.

The above information regarding both the prototype and known solutions in a similar field allows us to conclude that the new set of known and unknown features, which differs in both the technical nature of the features and their sequence and interconnection, ensures the achievement of a higher technical result in the proposed solution compared to the known level.

As a result of a search in patent and other technical sources of information, technical solutions were not identified that are characterized by a combination of features similar to the proposed solution, ensuring the achievement of similar results when using them. Distinctive features specified in the claims, clearly not following from the prior art, indicate the compliance of the proposed solution with the patentability criterion of "inventive step".

The essence of the proposed technical solution is illustrated by the schematic diagram of the installation for producing charcoal, shown in Fig. 1 as well as FIG. 2 corresponding to view “A” in FIG. 1 in section. In FIG. 3, 4, one of the possible embodiments of a removable device is presented.

The apparatus for producing charcoal is a horizontally located stationary object, made in such a way that the inner working space of the furnace is a looped channel 1, which allows the gas flow of the coolant to circulate in a full cycle repeat mode. The spatially thermally insulated casing 2 is divided into two chambers connected by a gas duct system 3. Any heat-resistant material that ensures minimal heat loss through the walls of the casing can be used as internal thermal insulation 4. In the front part of the first chamber, equipped with a door 5 for horizontal loading and unloading of withdrawal devices 6, there is a pyrolysis zone 7. The second chamber of the furnace body and part of the first operate in a gas-tight recuperator 8 made of heat-resistant brick. The recuperator 8 in FIG. 1 is shown schematically in the form of a combination of gas channels made of heat-resistant brick. The specific formation scheme (masonry) of the recuperator 8 depends on the productivity of the furnace, the power of the heat-resistant fan 9 and is carried out taking into account all the structural and technological requirements of the pyrolysis process in each case. To start the furnace with access to the operating mode, an external furnace 10 is used, which communicates with the pyrolysis chamber 7. The installation is equipped with an exhaust gas output system 11. A heat-resistant fan 9, a rotary gate 12 (see Fig. 2) and a gas-permeable recuperator 8 are installed inside the ring channel 1. In FIG. 2 schematically shows a rotary gate in two extreme positions: the gate is fully open and provides a maximum flow of circulating coolant - 12 '; the gate is completely closed for the period of loading and unloading of removable devices - 12 ''. One embodiment of the take-out device 6 is shown in FIG. 3, 4. The extraction device 6 is made in the form of a vertical strut 13, evenly provided over the entire height with fixing rods 14 directed upward and fixed at an angle to the vertical strut 13. On the rods 14 are wood briquettes 15.

Installation works as follows.

First, the furnace is started up and the furnace is brought to the operating temperature mode corresponding to 400 ÷ 450 ° C. To do this, in a portable furnace 10 burn any fuel, such as firewood. In this case, the working space of the furnace is uniformly heated throughout the entire looped channel 1 with the fan 9 operating and the gate open 12. When the operating temperature is reached, the supply of hot gases from the furnace 10 to the looped channel 1 is stopped. When the gate 12 is closed and the fan 9 is turned off, through the door 5 of the furnace body, horizontal loading of the extraction devices 6 is carried out in the pyrolysis zone 7. After the door 5 is closed, the gate 12 is opened and the fan 9 is turned on. Within 2 ÷ 3 hours, the process of charring the wood briquettes 15 is carried out directly their contact with the circulating flow of the gas coolant. The products of thermal decomposition of wood are removed from the pyrolysis furnace for utilization by burning, while the required temperature of the pyrolysis furnace is maintained by controlled intake of outside air into the pyrolysis chamber, by controlling the vacuum in the pyrolysis chamber due to the rotary gate. The end of the pyrolysis is determined visually by the nature of the exhaust gases.

Currently, the proposed device for producing charcoal has passed successful semi-industrial tests at one of the logging sites in Siberia. Charcoal productivity of 0.3 t / h was achieved. at the exit - 350 kg of charcoal per ton of briquettes. Actual performance is fully consistent with the estimated performance previously laid down in the design basis of the individual components of the device.

Tests of the device in industrial conditions have proved its operability and energy efficiency. Given the ease of manufacture and operation, we can recommend the proposed device for implementation in the production of charcoal with the possibility of implementation in a wide range of performance.

Claims (6)

1. Installation for producing charcoal, including a furnace body equipped with thermal insulation, a remote firebox communicating with a pyrolysis chamber containing removable devices for loading wood, a gas duct and an exhaust system, characterized in that the working space of the furnace is made in the form of a looped channel equipped with a heat-resistant fan, a rotary gate and a gas-permeable recuperator installed inside the looped channel, while the gas-permeable recuperator is made of heat-resistant th brick. 2. Installation for producing charcoal according to claim 1, characterized in that the mass of heat-resistant brick to perform a gas-permeable recuperator is not less than ten times the mass of wood loaded for pyrolysis. 3. Installation for producing charcoal according to claim 1, characterized in that the furnace body is equipped with a door for horizontal loading and unloading of removable devices. 4. Installation for producing charcoal according to claim 1, characterized in that each extraction device is made in the form of a vertical rack, evenly equipped throughout the entire height with fixing rods pointing upward and fixed at an angle to the vertical rack. 5. Installation for producing charcoal under item 1, characterized in that the rotary gate is installed in front of the door for horizontal loading and unloading of removable devices. 6. Installation for producing charcoal according to claim 1, characterized in that the fan is preferably installed behind the pyrolysis zone along the gas stream.

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