RU2749665C1 - Method for production and catalytic cracking of synthesis gas in vertical continuous gasification reactor - Google Patents

Abstract

FIELD: gas industry.

SUBSTANCE: invention relates to a method for thermal destruction of organic substances and waste ensuring production of synthesis gas without a liquid fraction. The method includes the stages wherein the source material with a fraction size of 1 to 5 mm and a moisture content of 4 to 12% is supplied by a screw conveyor equipped with a frequency drive into a vertical reactor including a body pierced with metal plates in simultaneous contact with flue gases and with the product of pyrolysis, as well as a rotor with blades arranged with the same pitch between the lower and the upper blades, by means of the rotary motion whereof the source material is moved upward passing through a chamber heated to the temperature of 750 to 850°C wherein the source material is separated into coke and a gas component. The coke mixed with gas then moves to the upper part of the reactor heated to temperature of 980 to 1000°C and constituting the cracking area, the time presence of the mixture in the cracking area is from 0.5 to 1.5 seconds, then the gas mixture is supplied through a branch pipe for cooling and cleaning before further use, the coke is transported by gravity through the unloading window down the accumulator into a spiral screw conveyor equipped with a water jacket and installed at an angle of 45° to the horizon, wherefrom it is unloaded into a storage hopper.

EFFECT: increased degree of purification of thermal processing products of organic waste prior to further processing thereof, removal of all volatile components from the coke prior to activation thereof and destruction of resinous compounds from the gas before prior to further purification thereof.

1 cl, 1 dwg

Description

The invention relates to a method for thermal destruction of organic substances and waste to obtain synthesis gas without liquid fraction.

The closest analogue of the patentable solution is patent RU 2725434 C1, published on 02.07.2020). The method includes feeding raw materials with a fraction size of 1-30 mm by a screw conveyor equipped with a frequency drive into a vertical feed chamber, including a rotor with blades, moving the raw material from bottom to top through a chamber heated to 900-950 ° C, in which the raw material decomposes into coke and the gas component, the gravity movement of coke from top to bottom along the accumulator connected to the upper part of the feed chamber to the screw spiral conveyor equipped with a water jacket, moving the coke along the conveyor from bottom to top at an inclination of 28-32 ° to the horizontal and simultaneous cooling, unloading the cooled coke into the storage hopper, removing the gas component from the upper part of the chamber through a branch pipe downward to the secondary heating zone of the combustion chamber, re-acting on gases with a temperature of 930-980 ° C for 1.5 seconds and removing gases from the lower part of the branch pipe into the further processing system before using.

The main disadvantages and differences of this method are:

1. The destruction of organic matter and the cracking of synthesis gas takes place in two units: a pyrolysis reactor and a recuperator system. The system of four recuperators is several times larger in size than the reactor. - Additional space will be required. Large dimensions of the recuperators will lead to additional heat loss.

2. The high temperature recuperator will be clogged with soot released during the cracking of synthesis gas. - This will affect the quality of the gas, the operation of the reactor will become cyclical and can lead to burnout of the recuperator.

The technical problem solved by the proposed invention consists in the development of a technology that ensures maximum purification of raw materials (son-gas and coke) obtained as a result of thermal processing of organic waste.

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

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

The claimed technical result is achieved by implementing the method of thermal destruction of free-flowing organic matter, including the stages at which the raw material with a fraction of 1-5 mm is fed by a screw conveyor equipped with a frequency drive into a vertical reactor, including a rotor with blades located at the same pitch from the lower blades to upper, by means of rotary motion of which the raw material is moved from bottom to top, passing through a chamber heated to 750-850 ° C, where the raw material decomposes into coke and a gas component. Further, coke mixed with gas moves to the upper part of the reactor, heated to 980-1000 ° C and representing a cracking zone. The residence time of the mixture in the cracking zone is from 0.5 to 1.5 seconds, after which the mixture of gases is fed through the nozzle for cooling and cleaning before further use. The coke is transported by gravity through the discharge window to the bottom along the accumulator, into a spiral screw conveyor equipped with a water jacket and installed at an angle of 45 ° to the horizon. Coke, moving along the conveyor from the bottom to the top, is cooled and discharged into the storage hopper.

A frequency drive is installed on the screw conveyor, which allows you to control the consumption of raw materials and the productivity of the installation, depending on the time the raw materials are 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 thermal processing of raw materials, as well as the time of cracking synthesis gas. The blades of the vertical shaft, placed with the same pitch, facilitate the movement of the raw material upward with simultaneous mixing, stabilize the flow, restrain the premature removal of the raw material from the reactor by gas, and the drive is controlled by a frequency converter. Reheating the mixture to 950-1000'C provides maximum separation of volatile components from coke with their transfer to the resulting gas and ensures the process of catalytic cracking of gas, in which all resinous compounds (naphthalene and paraffinic fractions) are sold into simple gases and soot. The catalyst is coke formed in the process of pyrolysis of organic matter fed into the reactor. To seal the reactor chamber, the conveyor is installed at an angle of 45 degrees to the horizon.

In the following, the solution is explained with reference to FIG. 1, which shows a diagram of a technological installation by means of which the method is carried out.

Solid raw material 1 (seed husks, sawdust, coal, etc.) with a size of no more than 5 mm and a moisture content of no more than 12% is fed by a screw conveyor 2 into the vertical chamber of the reactor 3. The screw 2 is equipped with a frequency drive and controls the consumption of raw materials and the productivity of the installation, which ranges from 0.5 to 3.0 t / h.

Further, the raw material, by a rotating shaft 5 with the help of guide vanes 6 with support from the screw conveyor 2, moves upward along the pyrolysis zone I of the reactor, heated by the flue gases of the burner to 750-850 ° C. The temperature is regulated by the capacity of the burner 7 and the exhaust fan 8, the more capacity, the higher the temperature in the pyrolysis zone. At temperatures above 850 ° C, the pyrolysis process changes from exothermic to endothermic, which leads to a significant increase in fuel consumption and a decrease in the reaction rate (destruction). The distance between the blades 6 is the same over the entire length of the shaft 5, this allows, by controlling the frequency of its rotation, to control the processes in the cracking and pyrolysis zone. For example, an increase in the speed of rotation of the shaft 5 will lead to more active mixing of the product in the pyrolysis zone, and the rapid rotation of the blades 6 in the cracking zone stabilizes the flow and restrains the premature ejection of coke from the reactor. The speed of passage of raw materials along the entire length of the reactor is limited by the screw conveyor 2 with a frequency drive. In the process of moving upward, the raw material quickly heats up, thanks to the original design of the reactor vessel 3, the contact area (ablation) of the product with the heated metal is doubled due to the piercing of the reactor vessel 3 with plates 4 being simultaneously in contact with the flue gases and with the pyrolysis product. The product heated without access to oxygen undergoes decomposition (destruction) into a carbon residue (coke), hydrogen, carbon monoxide and the simplest organic gases (methane, ethane and other hydrocarbons with impurities).

Further, the coke mixed with gas, under the action of the blades 6 and the released gas, moves to the upper part of the reactor (cracking zone II), heated to 980-1000 ° C, is regulated by the temperature of the flue gases in the burner 7. Reheating the mixture in the cracking zone to 950- 980 ° C provides the maximum separation of volatile components from coke with their transfer to the produced gas and provides a catalytic gas cracking process where all resinous compounds (naphthalene and paraffin fractions) decompose into simple gases and soot. The catalyst is coke formed in the process of pyrolysis of feedstock 1 supplied to the reactor. The residence time of the mixture in the cracking zone is from 0.5 to 1.5 seconds, it is set depending on the composition of the processed product 1, it is regulated by the capacity of the screw conveyor 2. After cracking, the gas mixture is fed through the branch pipe 9 for cooling and cleaning before further use. The coke moves by gravity through the unloading window to the bottom along the accumulator, into the screw spiral conveyor 11, equipped with a water jacket 10. To seal the reactor chamber 3, the conveyor 11 is installed at an angle of 45 degrees to the horizon. Coke, moving along the conveyor 11 from the bottom to the top, is cooled to 40 ° C and unloaded into the storage hopper.

All processes in the unit are optimized to maximize the removal of volatile hydrocarbons from the feedstock and to obtain high-quality homogeneous coke for its further activation to activated carbon, as well as to obtain synthesis gas. Syngas can be used as a gas fuel in third party systems. The invention has great flexibility and allows you to widely control the temperature, productivity, stirring speed in the reaction zone.

The main difference and advantages from all known installations is the effective combination of two processes in one installation: the pyrolysis process and the catalytic cracking of synthesis gas in a vertical continuous reactor.

The coke obtained in the pyrolysis zone is heated in the cracking zone to a temperature of 950 °. C and performs the functions of a catalyst, heat carrier, filter for soot released during the cracking of synthesis gas. Achieved by doubling the ablation surface area (installation of plates in the reactor vessel located in two chambers of heating and pyrolysis at the same time).

Due to the absence of a liquid fraction, there is no need for equipment for its processing.

Claims (1)

The method of thermal destruction of organic substances and waste with the production of synthesis gas without a liquid fraction, including the stages at which the raw material with a fraction of 1-5 mm and a moisture content of 4-12% is fed by a screw conveyor equipped with a frequency drive into a vertical reactor, including a case, pierced metal plates, which are simultaneously in contact with flue gases and with the pyrolysis product, as well as a rotor with blades placed with the same pitch from the lower blades to the upper blades, through the rotational movement of which the raw material is moved from bottom to top, passing through a chamber heated to 750-850 ° С, where the raw material decomposes into coke and a gas component, then the coke mixed with gas moves to the upper part of the reactor, heated to 980-1000 ° С and representing a cracking zone, the residence time of the mixture in the cracking zone is from 0.5 to 1.5 seconds, after which the gas mixture flows through the branch pipe for cooling and cleaning before further use, the coke moves by gravity through you the loading window down the accumulator into a spiral screw conveyor equipped with a water jacket and installed at an angle of 45 ° to the horizon, from where it is unloaded into the accumulation hopper.

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