HUP0800261A2 - Pyrolysis reactor and method - Google Patents

Description

(Figure 1)

6450R

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Pyrolysis equipment and process

The invention relates to a pyrolysis apparatus comprising a reactor unit with a heated pyrolysis space and a condensation unit for condensing pyrooil from the pyrogas by cooling the pyrogas extracted from the material in the pyrolysis space. The invention also relates to a pyrolysis process based on the apparatus.

Waste processing is becoming an increasingly important industry today. As a result of our lifestyle, large amounts of waste are continuously generated that do not decompose naturally, or only decompose very slowly. The storage and disposal of such waste are both costly, therefore one of the goals of waste processing is to extract as much and as high-quality recyclable material as possible.

One such process suitable for recovering recyclable materials is oxygen-free thermal decomposition, i.e. pyrolysis, during which waste containing large molecular organic compounds (e.g. rubber, plastics) is thermally decomposed to produce so-called pyrogas or pyrooil. The ratio and chemical composition of the end products depend on the raw materials (i.e. the type of waste) and the pyrolysis conditions. For pyrolysis, the waste is first usually shredded, then introduced into a pyrolysis reactor, where it is heated for a longer period of time in an oxygen-free environment, the pyrogases released as a result (i.e. the vapors and gases generated during pyrolysis) are drained off, and then precipitated in a cooling system, thus obtaining pyrooil, which can be used, for example, as heating oil or, with further processing, as engine fuel. The gases remaining after the vapors have been precipitated also have many uses. The soot remaining from the evaporated waste is a recyclable material, which can be used, e.g. It can be used as an additive in rubber production.

-2From the perspective of the continuity of the pyrolysis process, we distinguish between batch and continuous pyrolysis equipment. In the case of a batch-operated equipment, the pyrolysis reactor is filled with the waste serving as the raw material, and then, after a certain period of heat treatment, the remaining soot and other residues are removed. The reactor is heated within certain limits and then cooled back down, which results in significant energy loss. In addition to energy loss, the reactor material is destroyed prematurely due to thermal fluctuations, which are caused by the frequent alternation of contraction due to cooling and expansion due to heating. The intense volume change resulting from thermal fluctuations leads to rapid fatigue of the material structure, and the time spent on filling and emptying severely limits productivity. In contrast, in continuous equipment, the waste is continuously fed into the pyrolysis reactor, and the remaining material is continuously discharged from the reactor. The pyrogases and the pyro oils obtained from them are also generated continuously, the system requires less supervision, there is no need to repeatedly stop and restart individual processes. The present invention relates primarily to such continuous pyrolysis equipment.

When designing a reactor for continuous pyrolysis equipment, it is important to ensure that the waste remains in the reactor for a suitable period of time and at a suitable temperature. This is conveniently achieved by using a reactor consisting of several reactor chambers, the individual chambers of which can be heated to different temperatures. In the case of a pyrolysis equipment consisting of several reactor chambers, the chambers are typically arranged one after the other, and the waste is driven through each chamber by some kind of moving device, such as screws. An apparatus with such a pyrolysis reactor is described in US 4,983,278.

The disadvantage of known pyrolysis equipment and processes is that it is difficult to achieve rapid removal of the resulting pyrogases, which would be necessary for the faster course of the pyrolysis processes. The retention of the resulting pyrogases in the pyrolysis space leads to the formation of long-chain molecules, which reduces the quality of the pyrooil.

• · ·· ·· ··*· ······ · • · · 4 · ·

-3The aim of the invention is to create a pyrolysis device and method that is free from the above disadvantages of the prior art solutions. A further aim was to create a pyrolysis device and method that is simple and can be operated at low cost and that utilizes the resulting pyrogases in the most efficient way possible.

The invention was created by the realization that after the pyrooil has been precipitated from the resulting pyrogas, a drop-free pyrogas remains, which is suitable in all respects (composition, temperature) for being recirculated into the pyrolysis space to accelerate the removal of the newly formed drop-rich pyrogas.

The invention is therefore a pyrolysis apparatus according to the features of claim 1 and a pyrolysis method according to the features of claim 7. Preferred embodiments of the invention are defined in the subclaims.

The advantage of the invention is that the continuous, controllable recirculation of dry pyrogas allows the gases formed to be removed quickly. This speeds up the pyrolysis process and reduces the formation of long-chain molecules, thereby improving the quality of pyrooil and soot.

An exemplary preferred embodiment of the invention is described below with reference to the drawing, where the

Figure 1 is a technological diagram of a pyrolysis device according to the invention.

When designing the device according to the invention, it was an important aspect that the waste should stay in the reactor for a suitable time and at a suitable temperature. Therefore, the device was preferably designed to contain three reactors 1, 2, 3, which can be operated at different temperatures. The soot remaining from pyrolysis is a valuable recyclable material, the quality of which is important to maintain at the most appropriate level and ensure this in the long term. The device was designed so that in the pyrolysis space of the reactors there is an artificial

A gas stream is passed through, which accelerates the evaporation of gases produced during pyrolysis.

The device according to the invention therefore comprises 50 reactor units, which preferably have three reactors 1, 2, 3 arranged one above the other and connected in series with each other. The reactor unit 50 has 7 waste filling connections, 10 outlet openings, 21 pyrogas return connections and two gas discharge connections 23, 24. The flexible connection between the reactors 1-3 is ensured by compensators in the case of gravity overflows. All three reactors 1-3 have a means for ensuring material movement from the waste inlet to the outlet.

The material to be pyrolyzed, preferably waste, which can be, for example, a car tire, plastic film, plastic objects, parts or a mixture of these in any ratio, is chopped into pieces of about 2 - 5 cm before feeding. The material to be pyrolyzed, the waste to be processed, is continuously fed through the waste filling connection 7 formed on the body of the reactor 1. The material to be pyrolyzed reaches the outlet opening 10 from the waste filling connection 7 along the arrows indicated outside the reactors. A material conveying device is arranged in the reactor chamber 1a of the reactor 1, which is conveniently designed as a belt spiral fixed to an axis, and with the help of which the waste moves along the longitudinal direction in one direction (from left to right in the figure), while the blades placed on the belt spiral rotate and mix it. The waste passes from the reactor 1 to the reactor 2 by gravity through a through-flow fitting 8. Preferably, identical belt spirals are arranged in reactors 1 and 2; in the case of reactor 2, it moves the waste from right to left.

The material passes through the 9 through-flow fitting of the reactor 2 into the reactor 3. In the reactor 3, unlike the previous ones, the blades placed on the mixing arms fixed to the shaft perform the intensive mixing and force the material to move linearly from left to right. The evaporated and soot-transformed waste enters the temporary collection tank connected to the outlet opening 10 of the reactor 3. The waste introduced into the reactor unit 50 must therefore travel along the entire length of the reactor chambers 1a-3a ·· ·· ·· ·*» ······ ·

-5 to move through the gravity flow fittings 8, 9 to the chamber below. From the collection tank, the soot is discharged into further units at regular intervals through a valve.

Pyrolysis occurs continuously in the 50 reactor units, with the waste being propelled forward by means of conveyors within the reactor chambers, and the material being gravity fed from the upper chambers to the lower chambers. The time spent in each chamber and the temperature set in each chamber depend greatly on the type of waste. Pyrolysis temperatures are typically between 400 and 800 degrees, but can vary from chamber to chamber, and the time spent in each chamber is typically between 15 minutes and 25 minutes, but these values can vary significantly depending on the material being pyrolyzed.

The heating of the reactor unit 50 is carried out through the heating jackets 4-6 placed on the reactors 1-3. The heating jackets 4-6 are preferably in communication with each other, but not in communication with the pyrolysis space. The heating of the reactors 13 is carried out from the heating tube inlet 11 of the reactor 3 and from the heating tube inlet 13 of the reactor 2 along the arrows indicated in the heating jackets 4-6 to the flue gas discharge connection 15. The pyrolysis takes place in the longitudinal reactor chambers 1a-3a of the reactors 1-3, which are part of the pyrolysis space. The reactor chambers 1a-3a are preferably 3-10 m long, and their internal diameter is preferably between 20 cm and 1 m.

Reactors 1-3 require different temperature settings. Reactor 1 requires the lowest temperature, and reactor 3 the highest. The thermal afterburner heat of reactors 1-3 is distributed through a heating pipe and heated by forced circulation in heating jackets 4-6 surrounding the body of reactors 1-3. The main supply heating pipe is divided into three parts, of which 2 are connected to reactor 3 via heating pipe inlets 11. Along the forced circulation, the unused heat passes through the connecting piece 12 formed in the upper part of the heating jacket 6 to reactor 2, where a third heating pipe refreshes the flue gas through a heating pipe inlet 13. After the forced circulation in reactor 2, the heating flue gas passes without refreshing into reactor 1 via connecting piece 14. The flue gas leaves reactor 1 via the upper flue gas discharge connection 15. so 1 *· ·· ·· · · · · ······

-6 reactors also utilize the waste heat that reactor 2 cannot utilize.

The heating of the reactor unit 50 is carried out by a thermal afterburner 33 with a burner head, thus ensuring that the harmful substances in the flue gas are kept at a minimum level. The energy required for heating is generated from the gas obtained from pyrolysis. The system requires, for example, the use of pipeline gas. After a few hours of operation, pipeline gas becomes unnecessary because sufficient pyrogas is formed for the system to be self-sustaining. The hot flue gas, passing through the heating line 40, reaches the reactor unit 50 via a main line, where it is divided into three parts, two branches are connected to the heating tube inlet 11 of the reactor 3, and the remaining branch is connected to the heating tube inlet 13 of the reactor 2. The flue gas, having given up its thermal energy, exits through the flue gas discharge connection 15 of the reactor 1. The external jacket heating is therefore preferably designed as a continuous system heating the reactor chambers 1a-3a and containing at least one burner head.

The device operates at a pressure close to atmospheric pressure. According to the invention, the pyrolysis decomposition process takes place in an artificially produced gas stream. In Figure 1, the gas path 41 of the gas flow is marked with a dashed line. The advantage of the invention is that with the continuous, controllable gas flow, the gases formed can be quickly removed, and the formation of long-chain molecules is reduced, thereby improving the quality of other by-products, e.g. the quality of the pyro oil.

The pyrolysis device according to the invention therefore comprises a reactor unit 50 having a heated pyrolysis space and a condensation unit 51 which cools the pyrogas extracted from the material in the pyrolysis space and precipitates pyrooil from the pyrogas. According to the invention, after passing through the condensation unit 51, at least a part of the pyrogas is returned to the pyrolysis space of the reactor unit 50.

According to the preferred embodiment shown in the figure, the reactor chamber 3a of the reactor 3, which forms part of the pyrolysis space, is provided with a pyrogas return connection 21, and through it, the pyrogas is returned in a controlled manner by a fan 30, and is charged ·· · * · · «·«· • •a··· · • · · · · ·

-7the drop-free, so-called dry pyrogas passed through the condensation unit 51. The pyrogas, entrained by the drop-rich pyrogas formed in the reactor chamber 3a, passes through the connecting gas pipe 22 designed for undisturbed flow into the reactor chamber 2a, where it entrained further drop-rich gas and exits through the gas outlet connection 23. As the gas progresses, it is flowed against the material to be pyrolyzed and collides with several surfaces, which results in the majority of the particulate particles being precipitated while the gas continues to move. The gas exiting the gas outlet connection 23 reaches the condensation unit 51 through a vapor pipe, which is accelerated by the suction effect of the suction side of the fan 30, thus forming a circular connection. The gas formed in the reactor chamber 1a is conveyed via a separately designed gas discharge connection 24 to a cyclone 25 known per se, in which the water evaporated from the waste and carried by the pyrogas is condensed. No decomposition process has yet developed in the reactor chamber 1a. The gas leaving the cyclone 25 is also conveyed to the condensation unit 51 via the previously mentioned vapor pipe.

The 51 condensation unit shown in the figure contains first and second oil precipitation columns 26, 27. The pyrogas first enters the column 26, in which, moving upwards from the bottom of the tower, the high-boiling fraction is first precipitated, hitting the wall of the liquid-cooled column, and it is collected in the so-called boiling section. The precipitated, already lower-boiling fraction drips back from the gas that continues to flow into the drip tray formed in the upper part of the column 26. The pyrogas exiting the upper part of the column 26 reaches the bottom of the column 27 through a connecting pipe. Passing through the drip tray formed on two levels from the bottom of the column 27 upwards, the gas cools down to such an extent that no further liquid material is precipitated. The gas exiting the upper part of the column 27 is led to a gas scrubber 28 through a connecting pipe. The gas is cleaned of impurities by passing through an alkaline solution sprayed on two levels of the gas scrubber as it moves upwards in the gas scrubber. The gas leaving the gas scrubber 28 is led to a cyclone 29, where the entrained water droplets precipitate. Then the gas line connected to the pressure side of the fan 30 is divided into two branches, where part of the gas passes through a control valve towards the pyrogas return connection 21 of the reactor 3 and is re-entered into the cycle. The other part of the gas is sent to a compressor 31

-8, from where it is compressed and continues to the gas tank 32. From the gas tank 32, the gas reaches the thermal afterburner 33, from where it is burned with a burner to supply the series reactor with thermal energy, i.e. the part of the pyrogas not returned to the pyrolysis space is used to heat the reactor unit 50.

In the columns 26 and 27, e.g. four fractions are separated as condensate. The method of collecting them depends on the intended use. For heating purposes, e.g. they can be mixed, which results in an oil with a high heating value. The oil collected in the drip trays and collecting parts in the columns 26 and 27 is led through water separators 35 to oil ignition tanks 36. From the oil collecting tanks 36, the pyro oil is periodically pumped from the oil collecting tanks 36 via an oil line 43 to an interim storage tank 39 using a pump 38. The oil can settle in the tank divided into cells and then be pumped to other tanks.

Some water is produced during pyrolysis, and water is also found in the waste. Water is an undesirable substance in the technology, it must be separated and removed from the cycle. The separation is primarily carried out by precipitating the gas produced in reactors 1 and 2 with the help of cyclones 25. Further water separation is carried out with water separators 35 located at columns 26 and 27. The separated water here enters water collection tanks 37. From the water collection tanks 37, the water is supplied in a controlled amount by pumps 38 to the soot cooler 34 via water lines 42, where the cooling of the soot is assisted by water in the atomizers.

In the collection tank connected to the reactor 3, high-temperature soot is collected, which cannot be handled at high temperatures. As a further part of the technology, a soot cooler 34 cools the soot to a manageable temperature. The soot cooler 34 is preferably a piece of equipment that operates intermittently. Its outer shell is cooled by a coolant, and a mixing element in its interior rotates the soot. When the soot cooler is filled, a filling valve closes, and then intensive mixing begins, while a controlled amount of water collected in the technology is sprayed onto the soot. After a few minutes of cooling, the soot is emptied into the hopper located under the soot cooler 34, from where, after measurement, the soot is transferred for further processing, e.g. with the help of a conveyor screw.

The invention is of course not limited to the preferred embodiment described in detail, but further modifications and variations are possible within the scope of protection defined by the claims.

The choice of the number and placement of burners connected to the jacket heating depends largely on the thermal decomposition properties of the waste to be pyrolyzed. In the embodiment presented here, the reactor chambers 1a-3a are arranged directly above each other, which has the advantage of a compact, space- and material-saving structure, but it is obvious that the advantages of the invention are also realized in the case of arbitrarily arranged chambers. It is not absolutely necessary that the reactor chambers 1a-3a are arranged horizontally, nor that they are parallel to each other. The number of pyrolyzing reactor chambers 1a-3a can also be changed as required.

Claims (11)

-10Patent claims 1. Pyrolysis device, comprising a reactor unit (50) having a heated pyrolysis space and a condensation unit (51) for precipitating pyrooil from the pyrogas by cooling the pyrogas extracted from the material in the pyrolysis space, characterized in that after passing through the condensation unit (51), at least a part of the pyrogas is returned to the pyrolysis space of the reactor unit (50). 2. The apparatus according to claim 1, characterized in that after passing through the condensation unit (51), the pyrogas is divided into two parts, and the part of the pyrogas not returned to the pyrolysis space is used for heating the reactor unit (50). 3. The apparatus according to claim 2, characterized in that the pyrolysis space comprises at least one longitudinal reactor chamber (2a, 3a) which is provided with an external jacket heating not in communication with the pyrolysis space, in which reactor chamber (2a, 3a) a material conveying device suitable for conveying the material in one direction along the longitudinal direction is arranged, and in the reactor chamber (2a, 3a) the recycled pyrogas is flowed in the direction opposite to the material conveying direction. 4. The apparatus according to claim 3, characterized in that it comprises reactor chambers (1a, 2a, 3a) arranged one above the other, between which the material is conveyed by gravity, and the recycled pyrogas is circulated through at least two reactor chambers (2a, 3a) in a direction opposite to the direction of material conveyance. 5. The apparatus according to claim 4, characterized in that it comprises three reactor chambers (1a, 2a, 3a) arranged one above the other, and the recycled pyrogas is passed through the lower two reactor chambers (2a, 3a), wherein the external jacket heating is designed as a continuous system comprising at least one burner heating the reactor chambers (1a, 2a, 3a). 6. The apparatus according to any one of claims 1-5, characterized in that it comprises a gas scrubber (28) for cleaning the pyrogas from impurities after passing through the condensation unit (51) and before recirculation, and a cyclone (29) for extracting water droplets from the pyrogas. 7. Pyrolysis process, during which pyrogas extracted from a material in a heated pyrolysis space is cooled and pyrooil is separated from the pyrogas, characterized in that after the pyrooil has been precipitated, at least a part of the pyrogas is returned to the pyrolysis space. 8. The method according to claim 7, characterized in that after the pyrooil has been precipitated, the pyrogas is divided into two parts, and the part of the pyrogas not returned to the pyrolysis space is used for heating the pyrolysis space. 9. The method according to claim 8, characterized in that the pyrolysis space comprises at least one longitudinal reactor chamber (2a, 3a) which is provided with an external jacket heating not in communication with the pyrolysis space, in which reactor chamber (2a, 3a) the material is conveyed in one direction along the longitudinal direction, and in the reactor chamber (2a, 3a) the recycled pyrogas is caused to flow in a direction opposite to the material conveying direction. 10. The method according to claim 9, characterized in that the pyrolysis space comprises reactor chambers (1a, 2a, 3a) arranged one above the other, between which the material is conveyed by gravity, and the recycled pyrogas is caused to flow through at least two reactor chambers (2a, 3a) in the direction opposite to the direction of material conveyance. 11. The method according to any one of claims 7-10, characterized in that after the precipitation of the pyro oil and before the recirculation, a gas scrubber (28) is used to clean the pyrogas from impurities and a cyclone (29) is used to extract water droplets from the pyrogas.