RU2725434C1 - Method for thermal decomposition of loose organic matter in a vertical gasification reactor - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: invention relates to a method for thermal decomposition of organic substances and wastes. Method includes feeding raw material with size of 1–30 mm fraction with a screw conveyor equipped with a frequency drive, into a vertical supply chamber of raw material, which includes a rotor with blades, movement of raw materials from bottom to top through a chamber heated to 900–950 °C, in which the raw material decomposes into coke and a gas component, displacement by coke gravity from top to bottom along the accumulator connected to the upper portion of the feed chamber, into the screw spiral conveyor equipped with a water jacket, coke movement along conveyor from bottom to top at inclination of 28–32º to horizontal line and simultaneous cooling, unloading of cooled coke into accumulation bin, removal of gas component from upper part of chamber by means of branch pipe downwards back to zone of secondary heating of combustion chamber, repeated action on gases with temperature of 930–980 °C for 1.5 seconds and removing gases from the lower part of the branch pipe into a further processing system before use.EFFECT: invention increases efficiency and efficiency of processing organic substances and wastes, increases purification of processing products and improves properties of products, as well as possibility of controlling parameters of the process.1 cl, 2 dwg

Description

The invention relates to the field of processing of any organic substances and waste (husk of seeds, sawdust, etc.), by the method of thermal exposure without oxygen. The method is implemented using a vertical reactor and auxiliary systems combined into a single complex.

The following technical solutions are known from the prior art.

A known method of processing waste, including their gasification at 350-1000 ° C and treatment with a gasifying agent to the organic matter content in the waste below 100 g / t. Next, the resulting gas mixture is subjected to splitting at 950-1050 ° C for 1 s into low molecular weight compounds or elements that are introduced into water at 200-800 ° C for separation into synthesis gas and low molecular weight compounds. The synthesis gas is treated in the presence of a catalyst to produce liquid hydrocarbons or alcohols, gaseous hydrocarbons and carbon dioxide (patent RU No. 2014346, 04.04.1994).

The described method requires high energy costs, in addition, to maintain the heat balance of the process of gasification of organic waste, oxygen and hydrogen obtained by electrolysis of water, which is a very expensive process, are fed into the converter.

Also known is a method of destruction of organic waste, including: heating the material to a temperature sufficient to produce crude synthesis gas; burning raw synthesis gas to produce hot combustion gases; heat exchange between said combustion gases and a heat receiver for cooling the exhaust gas; cooling and wet cleaning said exhaust gas; monitoring the temperature of the exhaust gas after the specified exchange, but before the specified cooling and wet cleaning, and adjusting the parameters of the method to maintain the specified temperature of the exhaust gas above the level at which dioxins can form (RF patent No. 2524909, published 08/10/2014).

The closest analogue to the patented solution is the gasification method according to the patent of the Russian Federation No. 2360949, 07/10/2009, using a gasification reactor containing a boiler with two inner and outer shells concentrically arranged in one another, made in the form of annular heat-exchange shirts, with a gas duct between them, with a blade a raw material agitator and a truncated cone, zones of primary gasification and gas regeneration, a burner, a grate of a lance for feeding steam into the regeneration zone, a lid and a reversible drive mounted on it with an unconnected suction pipe with a pipe equalizer, with a paddle agitator attached to it and with tuyeres installed at the free end of the pipe to supply water vapor from the zone of accumulation of steam into the zone of primary gasification of raw materials.

The known method provides a two-stage production of gas with a calorific value of not higher than 1560 kcal, since the burning of excessively produced synthesis gas in the primary gasification combustion zone also contributes to a decrease in the calorific value of the gas, since a large amount of nitrogen is already present in the synthesis gas, and its combustion in This zone causes an increase in the amount of nitrogen, first in the primary gasification zone, and then in the resulting synthesis gas. In addition, the combustion of synthesis gas in the primary zone maintains a combustion temperature of 1500 ° C in order to raise the synthesis temperature to the maximum possible temperature in the regeneration zone, at the same time, this temperature contributes to the onset of NOx formation in the synthesis gas, and when using the obtained gas in gas piston power plants or in burners of heating systems, where the combustion temperature exceeds 1500 ° C, additional NOx is produced, which leads to environmental pollution.

The technical problem solved by the present invention is to develop a technology that provides the maximum purification of raw materials (syngas and coke) obtained as a result of thermal processing of organic waste.

The problem is solved by the structural components of the complex that performs thermal processing, allowing you to control the residence time of the starting material in the reactor and remove all volatile components from the feedstock, saturating the gas and improving the porous properties of coke, and simplifying the process of further gas purification. In addition, the proposed method uses a simplified design in comparison with the known complexes with high performance.

Thus, the technical result provided by the claimed invention is to increase the degree of purification of the products of thermal processing of organic waste before further processing, including the method allows you to remove all volatile components from coke before its activation and to destroy resinous compounds from gas before further purification.

The claimed technical result is achieved due to the implementation of the method of thermal destruction of bulk organic matter, which includes stages in which the raw materials with a particle size of 1-30 mm are fed with a screw conveyor equipped with a frequency drive into the vertical feed chamber, including a rotor with blades placed with an increasing pitch from the lower blades to the upper, through a rotational movement of which the raw materials are moved from bottom to top, passing through a chamber heated to 850-950 ° C, where the raw materials decompose into coke and a gas component, in the upper part the raw material supply chamber is connected to a storage device, through which the coke from the upper part the feed chamber flows by gravity from top to bottom into a screw spiral conveyor equipped with a water jacket, in which coke is cooled from the bottom to the top at a slope of 28-32 ° to the horizontal, from where the cooled coke is discharged into the storage hopper, and the gas component of the feed is removed from the top of the chamber feedstock by means of the pipe down to the secondary heating zone, where it is subjected to repeated exposure to a temperature of 930-980 ° C for 1.5 seconds and removed from the lower part of the pipe to the system for further gas treatment before use.

The frequency drive, which is part of the screw conveyor, allows you to control the consumption of raw materials and the performance of the installation, depending on the time spent by the raw materials in the reactor, which ensures the removal of all volatile components from the raw materials and the improvement of the porous properties of coke resulting from the thermal processing of raw materials. The blades placed with a variable pitch, increasing from the lower to the upper blades, contribute to the movement of raw materials up while tedding. Increasing the pitch between the upper blades compared to the lower ones allows you to change the mixing speed in the heating region without reducing the rotor speed and the speed of movement of raw materials from bottom to top, which also improves the porous properties of coke and ensures the separation of volatile components from coke and transfer them to the resulting gas. Reheating the evolved gases to 950 ° C for 1.5 seconds allows the destruction of resinous compounds (naphthalene and paraffin fractions) and significantly simplifies the process of further gas purification.

Further, the solution is illustrated by reference to the figures, which show the following.

Figure 1 - diagram of the technological installation by which the method is carried out.

FIG. 2 is a sectional view A-A of FIG. 1.

A solid substance (husk of seeds, sawdust, etc.) with a size of not more than 30 mm and a moisture content of not more than 12% is fed by a screw conveyor 1 into a vertical feed chamber with blades 2. The screw 1 is equipped with a frequency drive and controls the consumption of raw materials and plant performance, which ranges from 0.5 to 5.0 t / h.

Further, the raw material, using guide vanes with a feed of raw materials from the screw 1, enters the gasification chamber 5. The chamber 5 is heated by the flue gases of the burner to 850-950 ° C. At temperatures below 850 ° C, in addition to the solid and gas components, a liquid is formed, the processing of which requires additional labor costs, as well as additional actions necessary to remove liquid fractions from solid and gas products of thermal degradation. At temperatures above 950 ° C, additional nitrogen, sulfur and halogenated compounds are formed that can destructively affect the materials of systems devices for which syngas is intended. The frequency of the blades 4 on the hollow rotor 3 changes in the direction of reduction to the top. An increase in the distance between the blades, for example, by 1 cm compared to neighboring blades below (in other words, a gradually increasing distance between the upper blades compared to the lower ones) allows you to change the mixing speed in the heating region without reducing the rotor speed and the speed of movement of raw materials from below up.

When the rotor 3 rotates, the raw materials are mixed. The blades are made in such a way as to facilitate the movement of the raw material upwards, as well as to stir it. Limits the speed of passage of raw materials along the entire length of the reactor screw 1 with a frequency drive. In the process of moving up, the raw material quickly heats up and, without access to oxygen, undergoes decomposition (degradation) into carbon residue (coke), hydrogen, carbon monoxide and simple organic gases (methane, ethane and other hydrocarbons with impurities).

In the upper part of the gasification chamber, pyrolysis gases are discharged by the pipe 6 into the secondary heating zone, where they are subjected to repeated exposure to a temperature of 950 ° C for 1-2 (preferably 1.5) seconds. This effect is sufficient to destroy the structure of polyaromatic hydrocarbons (primarily the naphthalene group) and purify gases from tar vapors. The gases are then cooled for use in power plants.

The carbon residue of the upper blades is discharged into the accumulator 7. Next, the carbon residue by the screw conveyor 8 is discharged from the system. Coke is cooled to a temperature of <40 ° C in a screw conveyor 8 equipped with a water jacket 9. The direction of water flow into the nozzle of the water jacket 9 and the water outlet are shown by arrows. Chilled coke can be discharged into a storage bin or subject to further steam activation prior to activated carbon. The spiral design of the screw conveyor 8 and its inclination to the horizontal of 28-32 ° makes it possible to exclude the exit of pyrolysis gases from the reactor.

All processes occurring in the installation are optimized to maximize the removal of volatile hydrocarbons from raw materials and to obtain high-quality homogeneous coke for its further activation to activated carbon, as well as syngas production. Syngas can be used as gas fuel in third-party systems. The invention has great flexibility and allows you to widely control the temperature, performance, mixing speed in the reaction zone.

Claims (1)

A method of thermal degradation of bulk organic matter, comprising the steps of supplying a feed with a particle size of 1-30 mm with a screw conveyor equipped with a frequency drive to a vertical feed chamber including a rotor with blades, through the rotational movement of which the feed is moved from bottom to top passing through the chamber heated up to 900-950 ºС, where the raw material breaks up into coke and a gas component, in the upper part the raw material supply chamber is connected to the accumulator, by which the coke flows by gravity from top to bottom into a screw spiral conveyor equipped with a water jacket, in which from bottom to top at an angle of 28 -32º to the horizontal, while cooling, the coke is moved, from where the cooled coke is discharged into the storage hopper, and the gas component of the feed is removed from the top of the feed chamber by means of a pipe down to the secondary heating zone of the combustion chamber, where it is subjected to repeated exposure to a temperature of 930-980 ºС for 1.5 seconds and withdrawn from the bottom parts of the pipe into the system for further processing of gas before use.

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