Patent Application
20200291301
The invention relates to the field of organic substance processing, in particular to the method for processing the shredded wood waste, plant industry products, food industry waste, livestock and poultry waste. Products obtained during the thermal processing of organo-containing raw materials can be used as fuel.
In prior art there is a known method for ablative pyrolysis in a vertical cylindrical tank with a rotating rotor inside it which is located coaxially with the tank and have blades providing heating of raw material due to the contact with heated walls of the tank, with the output of solid fractions and steam through holes located near the tank bottom. (No. U.S. Pat. No. 8,128,717 B2, Mar. 6, 2012—Mechanically driven centrifugal pyrolyzer.
The disadvantage of this method is the impossibility of ensuring the same residence time of raw material particles in the reaction zone, that is, ensuring the same degree of raw material destruction and stable quality of the products obtained. In addition, the contact of raw material particles entering the reactor with ascending streams of vapour-gas degradation products being formed, as well as the partial condensation of these vapours on raw material particles lead to sticking of particles, clogging up of the space between blades and the rotor with the resulting mass, exclude the possibility of providing the necessary contact of the raw material with heated tank walls, make the heat exchange more difficult and thus eliminate the smooth operation and stable quality of resulting products.
Also, in the prior art there is a known method for ablative thermolysis, including hermetic supply of raw material particles, ablative thermolysis of raw material particles sandwiched between a rotating surface and a heated ablation surface, when raw material particles are moving during thermolysis along the ablation surface using the rotating surface, output of thermolysis products. (US 2005/0173237 A1, August 2005—Ablative thermolysis reactor.
Disadvantages of the prior art method are the difficulty of controlling the speed of raw material particles' axial movement and the required time of contact of raw material particles with the heated ablation surface and, therefore, the impossibility of ensuring stable quality of the products obtained, as well as the possibility of sticking and accumulation of particles between the rotating surface and the ablation surface with the formation of an annular plug between the rotating surface and the shaft. Sticking and accumulation of raw material particles occurs as a result of the contact of colder particles of the raw material entering thermolysis area with vapour-gas reaction products, and their partial condensation on the surface of particles. Such an accumulation can lead to the termination of the process and jamming of the device. In addition, it is extremely difficult to choose a material that ensures the stable operation of an elastic element at temperatures from 450 to 700° C., since the operating temperature range of structural materials providing elasticity is much less than 500° C.
The combination of the above factors leads to low efficiency and reliability of the design.
The closest method in regards to technical essence and achieved result is a method for thermal processing of organo-containing raw materials (RU No. 2395559, July 27, 2010), wherein the thermochemical conversion of organo-containing raw materials into gaseous and liquid fuels is implemented by heating first in the drying chamber by a drying agent with a temperature of 160-200° C., obtained by mixing flue gases that have passed through the pyrolysis chamber sleeve with air, and then by thermal decomposition without air access in the pyrolysis reactor to produce solid pyrolysis products and a vapour-gas mixture, with subsequent condensation of a part of the vapour-gas mixture into fluid fuel, wherein a part of the uncondensed vapour-gas mixture after preheating to a temperature of 450-520° C. is fed into the pyrolysis reactor in an amount that ensures the residence time of pyrolysis products in the pyrolysis chamber not more than 2 seconds and the excess pressure in the pyrolysis chamber at the level of 500-1000 Pa.
Disadvantages of this method are as follows: additional heat consumption for heating a part of the uncondensed vapour-gas mixture, which after the condensation of liquid fuel is supplied to the pyrolysis chamber; significant fluctuations in the residence time of raw material particles in the pyrolysis chamber, controlled by the amount of supplied recycled gas; gumming of parts of the power generation device with the exhaust part of the uncondensed vapour-gas mixture; and even higher sticking of raw material particles at the entrance to the pyrolysis chamber as a result of the circulation of fine mist of the dripping high-boiling liquid in a gas recirculation circuit, which leads to instability of the quality of raw material destruction products. In addition, the supply of circulating gas into the pyrolysis chamber leads to additional entrainment of fine coal into the gas recirculation circuit, deposition of this coal on walls of ducts, reduction of the working section of ducts and even greater instability of the pyrolysis process. The combined selection of a solid product (carbonaceous residue) and a vapour-gas mixture from the reactor leads to the adsorption of components of the vapour-gas mixture on the carbonaceous residue surface and a decrease in its quality.
Object of the invention is to increase the stability and efficiency of the process of thermochemical conversion of organo-containing raw materials, to increase the installation reliability and the quality of products.
Technical result of the claimed group of inventions is an increase in the efficiency of the process of thermochemical conversion of organo-containing raw materials, which consists in ensuring uninterrupted operation with consistently high quality of the products obtained. The technical result is achieved by a method for thermochemical conversion of organo-containing raw materials, the method comprising drying of said raw material, hermetic supply of said raw material into a pyrolysis reactor, thermal decomposition of said raw material without air access in the pyrolysis reactor to produce solid products and a vapour-gas mixture, subsequent separation of said vapour-gas mixture by condensation into liquid products (a condensed part of the vapour-gas mixture) and gaseous products (an uncondensed part of the vapour-gas mixture), wherein (i) after drying and before supply into the pyrolysis reactor, the organo-containing raw material is preheated to a temperature close to, but not exceeding a thermal decomposition initiation temperature of the least thermally stable component of said organo-containing raw material; (ii) surfaces of a chamber of the pyrolysis reactor are heated to a temperature which excludes condensation of the vapour-gas mixture, and a heating temperature of the raw material is controlled by duration of stay in a preheating zone; (iii) the thermal decomposition is implemented in a form of the following successive stages occurring in corresponding zones of the pyrolysis reactor, said zones are configured to have an independent temperature control: a primary pyrolysis, where the raw material is converted into solid products and the vapour-gas mixture; a purification of the vapour-gas mixture, wherein after the primary pyrolysis the vapour-gas mixture is cooled to a temperature, under which a condensate is formed from a part of the vapour-gas mixture, the formed condensate is returned and mixed with the solid products and unreacted parts of the raw material; and a secondary pyrolysis, wherein the formed gaseous products together with the primary pyrolysis vapour-gas mixture are returned to the purification stage, and solid products are withdrawn from the secondary pyrolysis zone, preventing their contact with the primary pyrolysis vapour-gas mixture.
In a particular embodiment of the claimed technical solution, the condensation is implemented in three successive stages: primary cooling of the vapour-gas mixture in the vapour-gas mixture purification zone of the pyrolysis reactor; condensation of the vapour phase in the condenser; separation of an uncondensed part of the vapour-gas mixture from the dripping liquid with recirculation of a part of the gaseous product through the pyrolysis reactor cleaning zone.
In a particular embodiment of the claimed technical solution, the primary pyrolysis is implemented mainly in the mode of mechanical ablation. In a particular embodiment of the claimed technical solution, zones of primary and secondary pyrolysis provide the possibility of independent purging with an inert gas or a gas having reducing or oxidizing properties heated to a required temperature.
The technical result is also achieved due to the fact that in the installation for thermochemical conversion of organo-containing raw materials, comprising a drying chamber, a hermetic raw material supply chamber, a pyrolysis reactor having a surface rotating with at least one blade and a rotation axis coinciding with the longitudinal axis of the pyrolysis reactor, and at least one ablation surface of circular or elliptical section, perpendicular to the rotation axis of the rotating surface, a device of independent and elastic setting of the inclination angle of blades, a condensation unit consisting of a mass transfer apparatus and a separator, the hermetic raw material supply chamber is equipped with raw material heating means, and the pyrolysis reactor workspace is divided along the path of raw materials into the following successive zones equipped with independent heating devices—a primary pyrolysis zone, a vapour-gas cleaning zone, equipped with a device for separation and return of incomplete destruction products, and a secondary pyrolysis zone.
In a particular embodiment of the claimed technical solution, blades are hinged on the rotating surface of the pyrolysis reactor and have at least one degree of freedom.
In a particular embodiment of the claimed technical solution, the device for independent and elastic setting of the inclination angle of blades has a kinematic connection with them, is removed from the high temperature zone, is isolated from the impact of the vapour-gas mixture being formed and is capable of providing elastic pressure with required periodicity and force in the direction towards both the ablation surface and the rotating surface.
In a particular embodiment of the claimed technical solution, the elasticity in the device for independent and elastic setting of the inclination angle of blades is achieved by pneumatic, mechanical, electromagnetic and other methods.
In a particular embodiment of the claimed technical solution, blades are placed on the rotating surface of the pyrolysis reactor offset from each other along the length and radius of the rotating surface, in particular, along the helical line.
In a particular embodiment of the claimed technical solution, geometry of the ablation surface of the pyrolysis reactor is made in the form of a helical surface with variable or constant pitch, wherein the helical surface can be made without gaps or by individual sections.
In a particular embodiment of the claimed technical solution, heating devices of each of the three zones of the pyrolysis reactor have the possibility of independent temperature control.
In a particular embodiment of the claimed technical solution, the condensation unit separator is connected by pipeline to the reactor cleaning zone.
Details, features, and advantages of this group of inventions follow from the below description of embodiments of the claimed technical solutions using the drawings which show:
In the figures, numbers denote the following positions:
1—drying chamber; 2—chamber for hermetic supply of raw materials; 3—pyrolysis reactor; 4—device for independent and elastic setting of the inclination angle of blades; 5—device for separation and return of incomplete destruction products; 6—condensation unit; 7—separator; 8—firebox; 9—coal out-feed device; 10—blades; 11—pneumatic cylinders.
To solve the object, in the method for thermochemical conversion of organo-containing raw materials, including drying, hermetic supply of raw materials to the pyrolysis reactor, thermal decomposition of raw materials without air access in the pyrolysis reactor to produce solid products and vapour-gas mixture, the subsequent separation of it by condensation into liquid products (a condensed part of the vapour-gas mixture) and gaseous products (an uncondensed part of the vapour-gas mixture), after drying the organo-containing raw material before supply into the pyrolysis reactor is preheated to a temperature close to, but not exceeding the initiation temperature of thermal decomposition of the least thermally stable component of organo-containing materials, wherein surfaces of the chamber are heated to a temperature which excludes the condensation of pyrolysis vapour-gas products, and raw material heating temperature is controlled by duration of stay in the preheating zone; thermal decomposition is implemented in the form of the following successive stages occurring in corresponding zones of the pyrolysis reactor, having the possibility of independent temperature control:
primary pyrolysis, during which thermochemical conversion of raw materials into solid products and vapour-gas mixture is implemented mainly in the mode of mechanical ablation, without excluding the use of other methods,
purification of the vapour-gas mixture, which consists in its withdrawal from the primary pyrolysis zone, cooling to a temperature that ensures the vapour-gas mixture purification from a part of solid and unreacted products withdrawn with it, return and mixing of these products with solid primary pyrolysis products,
and secondary pyrolysis, wherein vapour-gas products formed are withdrawn together with the primary pyrolysis vapour-gas mixture through the zone and the installation for purification of the vapour-gas mixture and removal of solid products from the pyrolysis chamber, excluding their contact with the primary pyrolysis vapour-gas mixture,
wherein zones of primary and secondary pyrolysis provide the possibility of independent purging with an inert gas or a gas having reducing or oxidizing properties heated to a required temperature;
condensation is implemented in three successive stages: primary cooling of the vapour-gas mixture in the vapour-gas mixture purification zone of the pyrolysis reactor; condensation of the vapour phase in the condenser; separation of an uncondensed part of the vapour-gas mixture from the dripping liquid with recirculation of a part of the gaseous product through the pyrolysis reactor cleaning zone.
The installation for thermochemical conversion of organo-containing raw materials includes a drying chamber (1), a chamber for hermetic supply of raw materials (2), a pyrolysis reactor (3), a condensation unit (6) and a firebox (8). The drying chamber is connected by transport devices through metering devices with the chamber for hermetic supply of raw materials and the firebox. In a particular embodiment, such transport devices are screw conveyors (they are not conventionally shown in the diagram).
The condensation unit includes mass transfer devices located in series—a condenser and a separator.
The pyrolysis reactor workspace is divided into three zones: the first zone along the path of raw materials—a primary pyrolysis zone, the second zone—a vapour-gas mixture purification zone equipped with a device for separation and return of incomplete destruction products, and the third zone—a secondary pyrolysis zone. The pyrolysis reactor is equipped with an ablation surface that is capable of independently controlling the temperature in each zone.
The pyrolysis reactor is equipped: in the primary pyrolysis zone, with a nozzle connecting the reactor to the chamber for hermetic supply of raw materials; in the purification zone, with pipes for withdrawal of the vapour-gas mixture after purification to the condenser and for supply of a part of the gaseous product after the separator to cool the primary pyrolysis vapour-gas mixture; in the secondary pyrolysis zone—with a coal out-feed device.
The pyrolysis reactor is also equipped with a rotor, on the rotating surface of which blades are located with a gap in length and radius that have a kinematic connection with the device for independent and elastic setting of the inclination angle of blades. The device for independent and elastic setting of the inclination angle of blades is offset from the high temperature zone and isolated from impact of the resulting vapour-gas mixture. Independent elastic setting of the angle and force of blades pressing can be done by mechanical, electromagnetic, pneumatic and other methods. In a particular embodiment, it is implemented using the pneumatic method with the help of pneumatic cylinders and a distributor.
For this purpose, in the installation for thermochemical conversion of organo-containing raw materials, comprising a drying chamber, a hermetic raw material supply chamber, a pyrolysis reactor having a surface rotating with at least one blade and a rotation axis coinciding with the longitudinal axis of the pyrolysis reactor, and at least one ablation surface of circular or elliptical section, perpendicular to the rotation axis of the rotating surface, a device of independent and elastic setting of the inclination angle of blades, a condensation unit consisting of a mass transfer apparatus and a separator, the hermetic raw material supply chamber is equipped with raw material heating means, and the pyrolysis reactor workspace is divided along the path of raw materials into the following successive zones equipped with independent heating devices—a primary pyrolysis zone, a vapour-gas cleaning zone, equipped with a device for separation and return of incomplete destruction products, and a secondary pyrolysis zone, wherein blades are hinged on the rotating surface of the pyrolysis reactor and have at least one degree of freedom; the device for independent and elastic setting of the inclination angle of blades has a kinematic connection with them, is removed from the high temperature zone, is isolated from the impact of the vapour-gas mixture being formed and is capable of providing elastic pressure with required periodicity and force in the direction towards both the ablation surface and the rotating surface; the elasticity in the device for independent and elastic setting of the inclination angle of blades is achieved by pneumatic, mechanical, electromagnetic and other methods; blades are placed on the rotating surface of the pyrolysis reactor offset from each other along the length and radius of the rotating surface, in particular, along the helical line; geometry of the ablation surface of the pyrolysis reactor is made in the form of a helical surface with variable or constant pitch, wherein the helical surface can be made without gaps or by individual sections; heating devices of each of the three zones of the pyrolysis reactor have the possibility of independent temperature control; the condensation unit separator is connected by pipeline to the reactor cleaning zone.
Heating of organo-containing raw materials after drying before supply to the pyrolysis reactor in the chamber for hermetic supply of raw materials equipped with heating means to a temperature close to, but not exceeding the temperature of thermal decomposition of the least thermally resistant component of organo-containing raw materials, allows partially removing the raw material heating zone from the reactor, eliminating the possibility of condensation of vapour-gas mixture products on raw material particles entering the reactor from the drying bin, and increasing the efficiency of heat exchange in the reactor.
Wherein, surfaces of the hermetic supply chamber are heated to a temperature that prevents condensation of the pyrolysis vapour-gas products, which reduces the process efficiency and the quality of final products. Control of the raw material preheating temperature by residence time allows effectively using the method and installation for various types of raw materials and excluding thermal decomposition in the chamber for hermetic supply of raw materials.
The thermal decomposition is implemented successively in three stages in corresponding zones of the pyrolysis reactor (primary pyrolysis zone, vapour-gas mixture purification zone, secondary pyrolysis zone), which have the possibility of independent temperature control, which allows implementing the conversion of organo-containing raw materials with maximum efficiency and consistently high quality of final products, and implementing purification of the vapour-gas mixture from volatile fine coal forming in the presence of the vapour-gas mixture a layer of resinous unreacted product at the reactor outlet, its return to the reaction zone, thereby preventing a reduction in the cross section of gas ducts, sticking and clogging of the installation assemblies, eliminating sorbtion of the vapour-gas mixture by carbonaceous residue located in the secondary pyrolysis, thereby increasing the reliability of the coal out-feed device and the quality of coal produced, as well as improving the quality of liquid products.
The sequential arrangement of the pyrolysis reactor zones prevents the incoming raw materials from contact with thermal decomposition products, as well as the contact of coal in the secondary pyrolysis zone with the primary pyrolysis vapour-gas mixture, which improves the quality of the coal being fed out by reducing the content of products of secondary vapour-gas mixture decomposition.
The condensation implemented in three successive stages (primary cooling of the vapour-gas mixture in the vapour-gas mixture purification zone of the pyrolysis reactor; condensation of the vapour phase in the condenser; separation of an uncondensed part of the vapour-gas mixture from the dripping liquid with recirculation of a part of the gaseous product through the pyrolysis reactor cleaning zone) allows increasing the efficiency of separation of products being condensated and dripping liquids from gaseous products, excluding catalytic acceleration of the resinification reaction in the vapour-gas mixture, reducing the temperature gradient in the condenser by supplying the vapour-gas mixture cooled in the pyrolysis reactor purification zone, increasing the efficiency of further use of gaseous products, in particular to generate electricity by reducing the content of dripping liquid.
The primary pyrolysis implemented in the mode of mechanical ablation allows reducing the requirements for particle size, in particular, allows processing particles up to 50 mm in size, reducing the cost for preliminary grinding of raw materials.
Independent purging by an inert gas or a gas with reducing or oxidizing properties heated to the required temperature in the primary and secondary pyrolysis zones allows improving the conditions of primary pyrolysis and the quality of coal. Purging by inert gas eliminates the effects of air entering the reaction zone, thereby increasing the installation safety. Purging by gas with reducing properties allows increasing the carbon content in the coal produced by converting some of substances adsorbed by the coal into carbon. Purging by gas with oxidizing properties allows the activation process of coal, improving porosity and sorption capacity, which will also improve its quality.
The hinge fixing of blades on the rotating surface of the pyrolysis reactor and providing them with at least one degree of freedom allows self-regulating and reliable pressing of particles to the ablation surface depending on various parameters (particle size of raw materials, etc.) during operation, as well as to the rotation surface during periodic cleaning.
The removal of the device for independent and elastic setting of the inclination angle of blades from the high temperature zone and its isolation from the aggressive impact of the resulting vapour-gas mixture ensures uninterrupted stable operation of the reactor and the installation as a whole, as well as the pyrolysis process reliability.
Ensuring the possibility of elastic pressing of a blade with the required periodicity both to the ablation surface and to the rotating surface allows for periodic high-quality cleaning of the reactor assemblies from raw material particles during continuous operation.
Location of blades on the rotating surface of the pyrolysis reactor offset from each other along the length and radius of the rotating surface, in particular, along the helical line, as well as making the surface geometry of the pyrolysis reactor ablation in the form of a helical surface with variable pitch allow providing the controlled axial movement of raw material particles along the pyrolysis reactor ablation surface.
Thus, the proposed method allows increasing the stability and efficiency of the process of thermochemical conversion of organo-containing raw materials, and increasing the installation reliability and the quality of products.
The installation works as follows. Organo-containing raw material enters the drying chamber (1), where moisture is removed from it to achieve a moisture content of not more than 10% abs. wt. Drying is implemented by a drying agent obtained by mixing flue gases from the pyrolysis reactor sleeve (3) with air. The dried organo-containing raw material enters the chamber for hermetic supply of raw materials (2), where it is heated to the temperature at which thermal decomposition begins. In a particular embodiment, heating to the temperature of thermal decomposition is implemented through the wall by flue gases from the reactor. Wherein, surfaces of the chamber for hermetic supply of raw materials can be heated significantly above the temperature of thermal decomposition to prevent condensation of vapour-gas products, and the heating of raw materials is controlled by duration of stay in the chamber.
Particles of the heated raw material entering the pyrolysis reactor (3), despite the polydisperse composition, are firmly pressed by blades of the rotating surface to the hot ablation surface, as a result of which the thermochemical conversion of organo-containing raw materials occurs. Pressuring of raw material particles by blades is ensured by means of the device (4), wherein the kinematic connection of pneumatic cylinders with blades is provided by coaxial shafts as the option of a specific embodiment. Wherein, the device (4), which includes a pneumatic distributor and pneumatic cylinders, is withdrawn from the high temperature zone and is isolated from the impact of the vapour-gas mixture being formed (
The ablation surface geometry in the form of a helical line and the arrangement of blades along the helical line provide the axial displacement of solid particles of the raw material set by the helical line pitch and the rotor speed. Since the amount of solid particles decreases during the thermochemical conversion of the feedstock, the process stability along the pyrolysis reactor (3) axis is ensured by the variable pitch of the helical line along the reactor length and the controlled force of pressing the blades. After the raw material has passed the primary pyrolysis zone, the resulting vapour-gas mixture with a certain amount of volatile fine carbonaceous residue, formed as a result of a fairly intensive mechanically activated treatment (ablation), enters the device for separation and return of incomplete destruction products (5).
The finely dispersed volatile coal in the form of a resinous unreacted product (products of interaction) accumulated on walls of the device for separation and return of incomplete destruction products (5) saturated with vapour and partially condensed by decomposition products returns with the remaining solid carbonaceous residue into the secondary pyrolysis zone for calcining and further through the coal out-feed device 9 into a coal collector. The vapour-gas mixture purified from incomplete destruction products is fed to the condensation unit (6) for condensation (condenser) and for separation of the droplet-phase condensate in the form of a mist from non-condensable gas (separator). Wherein, the separator can be either of inertial type or in the form of an electrostatic precipitator. Then, a part of cooled gaseous products is fed by a fan to the vapour-gas mixture purification zone of the pyrolysis reactor (3).
Mixing of a hot vapour-gas mixture with cooled gaseous products promotes volumetric condensation of vapours, coagulation and precipitation of condensate droplets and particles of fine volatile coal on working surfaces of the device for separation and return of incomplete destruction products in the form of a resinous unreacted product (interaction products). Interaction products periodically, but during continuous operation of the pyrolysis reactor (3), are forcibly separated from walls and other structural elements of the device for separation and return of incomplete destruction products (5) and returned to the pyrolysis reactor.
In a particular case, independent heating of each zone of the pyrolysis reactor is performed by feeding flue gases obtained by burning fuel in the furnace (8) into the reactor sleeve, after mixing them with air to provide the necessary temperature conditions for the pyrolysis process. After passing through the pyrolysis reactor (3) sleeve and mixing with air, flue gases are first fed into the chamber for hermetic supply of raw materials to heat them to a temperature close to, but not exceeding the temperature of thermal decomposition of the least thermally resistant component of the organo-containing material, and then to the drying chamber—as a drying agent. Below, we list the main operating parameters and design characteristics for wood raw materials, as a specific use of the method and installation for thermochemical conversion of organo-containing raw materials.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/RU2016/000324 | 5/30/2016 | WO | 00 |
