Single-stage process and device for producing reformed pyrolysis oil and hydrogen-rich pyrolysis gas

Abstract

The invention relates to a process for producing pyrolysis oil, pyrolysis gas and pyrolysis coke, in which process a starting material, which substantially comprises biomass, is supplied to a pyrolysis reactor in the upper region thereof. The reactor comprises a substantially vertical reactor chamber which is substantially tubular. A packed bed of a bulk material is present in the reaction chamber, which bulk material comprises the starting material to be pyrolysed and, optionally, the pyrolysis coke. This bulk material is thermally treated in the pyrolysis reactor, wherein the pyrolysis coke, the pyrolysis gases and the pyrolysis vapours are formed from the starting material to be pyrolysed, and wherein the bulk material, the pyrolysis gases and the pyrolysis vapours are conducted through the reaction chamber from top to bottom. The movement of the bulk material is brought about substantially by gravity, and the movement of the pyrolysis gases and the pyrolysis vapours is brought about by the gas pressure that is building up. The thermal treatment takes place at least at a first temperature level of 300 to 650°C and subsequently at a second temperature level, which is higher than the first temperature level, of 450 to 900°C.

Description

[0001] Patent application:

[0002] One-step process and apparatus for producing reformed pyrolysis oil and hydrogen-rich pyrolysis gas

[0003] Applicant:

[0004] Fraunhofer Society for the Promotion of Applied Research

[0005] The application relates to a process and a reactor for the thermal conversion of biomass into oil, gas, and coke by simultaneously conducting pyrolysis and reforming in the same reactor. The resulting oil, gas, and coke are precursors for fuels, chemicals, and even pure hydrogen.

[0006] In the thermo-chemical conversion of biomass and biogenic residues, it is necessary to produce high-quality products, such as thermally stable oil and hydrogen-rich gas, to maximize economic efficiency. At the same time, simple yet robust reactors must be used. To generate these high-quality products, a two-stage process is currently used: thermocatalytic reforming (TCR) (described, for example, in M. Elmously et al. Ind. Eng. Chem. Res. 2019, 58, 35, 15853 ff). The high product quality in this process is ensured, among other things, by a medium-length heating phase of the biomass in the pyrolysis reactor and the reforming of the pyrolysis vapors.

[0007] From an economic perspective, it is desirable to simplify the complexity of reactors for the thermo-chemical conversion of biomass and - especially for small-scale applications - to implement a less complex, preferably single-stage process with which hydrogen-rich pyrolysis gas and pyrolysis oils of good quality can be obtained.

[0008] This problem is solved by the subject matter of the independent claims.

[0009] The dependent claims and the description teach advantageous developments. The present application describes a process in which pyrolysis and reforming are carried out simultaneously in a single reactor, i.e., combined in a one-pot synthesis. This approach eliminates the need for the investment-intensive Auger reactor in pyrolysis in thermocatalytic reforming (TCR).

[0010] In its most general form, the process according to the application is characterized by:

[0011] - the provision of a starting material comprising essentially biomass, in particular in lumpy form;

[0012] - feeding the starting material to a reactor having a substantially vertically arranged reactor chamber, wherein the reactor chamber is substantially tubular, in particular substantially cylindrical and / or substantially conical, wherein the starting material is fed into the upper region of the pyrolysis reactor, so that a bed of bulk material is present in the reaction chamber, wherein the bulk material comprises or consists of both the starting material to be pyrolyzed and the pyrolysis coke formed by the pyrolysis; the thermal treatment of the starting material in the pyrolysis reactor substantially in the absence of oxygen by means of at least one heating device for the reactor chamber, wherein thermal energy is introduced into the starting material by the heating device and the pyrolysis coke, the pyrolysis gases and the pyrolysis vapors are formed from the starting material to be pyrolyzed, and wherein the bulk material,the pyrolysis gases and the pyrolysis vapors are guided from top to bottom through the reaction chamber, wherein the movement of the bulk material through the reaction chamber is caused essentially by gravity and the movement of the pyrolysis gases and the pyrolysis vapors through the reaction chamber is caused essentially by the gas pressure built up by the thermal treatment of the starting material, and wherein the thermal treatment takes place at least at a first temperature level of 300 to 650 °C, in particular 300 to 500 °C, for example 350 to 450 °C or 300 °C to 400 °C and subsequently at a second temperature level of 450 to 900 °C, preferably 500 to 800 °C, for example 550 °C to 650 °C or 550 °C to 750 °C, which is higher than the first temperature level; as a rule, the temperature difference between the first and the second temperature level is then at least 100 °C,often at least 200 °C, often at least 250 °C (where the temperature difference of at least 200 °C or at least 250 °C is typically achieved especially when the first temperature level is 450 °C or lower); the residence time of the bulk material (in the reaction chamber) is 1 to 1200 minutes, in particular 3 to 600 minutes: typically, relatively long residence times are more advantageous; due to the better heat input, particularly in small-scale plants, residence times of 1 to 60 minutes or 3 to 30 minutes can also be useful in order to realize cost-effective plants; residence time is understood to be the time during which the thermal treatment takes place, i.e. the time during which the starting material or the bulk material is exposed to a temperature that corresponds at least to the temperature of the first temperature level;

[0013] - the separation of the pyrolysis gases and pyrolysis vapors obtained by the pyrolysis described above via an outlet arranged in the lower region of the pyrolysis reactor and separation of the pyrolysis coke via a discharge device arranged in the lower region of the pyrolysis reactor and optionally provision of pyrolysis oil by proportional condensation of the separated pyrolysis gas.

[0014] The reactor chamber is arranged essentially vertically. This means that deviations from an exact vertical alignment of up to 40° are possible. It is preferred that the deviation from an exact vertical alignment be less than 20°; for example, the deviation can also be less than 10°. According to the application, essentially cylindrical and / or essentially conical means that deviations from a circular or oval cross-sectional area are possible. In the essentially conical embodiment, the cross-sectional area of ​​the reactor chamber decreases from bottom to top. Such an embodiment has the advantage that a possible blockage in the reactor can be counteracted.The essentially vertical orientation is particularly important because no, or at least no significant, devices for transporting the bulk material through the reaction chamber are provided in the reaction chamber (i.e., the chamber in which the thermal treatment of the bulk material takes place). The vertical orientation therefore ensures that gravity can act on the bulk material, allowing it to move through the reaction chamber (hence the term "downtube reactor" is used below). It goes without saying that the closer the orientation of the reactor chamber corresponds to a precisely vertical orientation, the better the effect of gravity. The same applies to the essentially cylindrical geometry; this ensures that the starting material is efficiently conveyed through the reactor and can be thermally treated entirely in the reactor.

[0015] With the process according to the application, even very small-scale applications can be implemented economically, which is a huge advantage, especially for biomass processes, as these are highly decentralized. Recycling centers (biowaste) or even larger agricultural companies could be considered as operators for these small-scale plants. The reactors used according to the application can therefore be implemented particularly in small-scale plants with a biomass throughput of 1 kg to 500 kg per hour. However, the plants can also be built larger, e.g., up to a throughput of 1500 to 3000 kg / h. The diameter of the reactor must generally be larger than for small reactors.Since the heat input into the biomass is the decisive factor in these types of plants, this heat input can be achieved in larger plants by means of heating lances or, depending on the orientation of the reactor, essentially vertical channels (particularly heating gas channels) inside the reactor. This means that reactor diameters of a few centimeters up to 1.5 meters or more can easily be realized. Larger diameters of up to 2.5 meters or even up to 5 meters can also be realized, for example in designs where the reactor enables good heat input into the bulk material and / or biomasses where heat input can occur relatively quickly. These diameters can particularly be achieved when heating lances, heating gas channels or the like are used in the reactor.

[0016] This can be carried out for both a cylindrically constructed and a conically designed reactor; even rectangular arrangements are conceivable. All of these geometries are summarized under the term "tubular" in the application, since the most important aspect of the process according to the application is the movement of the bulk material consisting of the starting material to be pyrolyzed and, if appropriate, the pyrolysis coke through the reactor by means of gravity. The decisive factor here is not the horizontal geometry of the reactor, but essentially the unhindered movement of the bulk material inside the reactor. This is particularly well achieved if the reactor contains no conveying devices, in particular no conveying devices such as screws and the like, and the vertical region of the reactor is essentially characterized only by a largely smooth surface.

[0017] As already explained, the process according to the application is carried out in a vertically arranged, gravity-driven reactor. In this reactor arrangement, the resulting "pyrolysis vapors" must flow through the fixed bed from top to bottom due to the pressure built up by their generation and leave the reactor – after passing through at least two temperature levels – in the lower region of the reactor, e.g., at the bottom. Strictly speaking, in the case of an integrated riser, pyrolysis gases and pyrolysis vapors usually leave the reactor at the top of the reactor; however, here too, the separation of gases / vapors and pyrolysis coke takes place in the lower region of the reactor. Since the reactor is pressure-tight and sealed by a lock on the inlet side, and a similar lock system is or can be arranged on the solids side (coke discharge), the "pyrolysis vapors" formed in the reactor increase the pressure within the reactor.If the pressure generated in the reactor is higher than the pressure drop generated by the fixed bed, the pyrolysis vapors pass through the fixed bed and leave the reactor towards the condensation stage. Since the reactor is continuously fed with feedstock, at least in continuous operation, the formation of pyrolysis vapors occurs continuously and thus pyrolysis vapors also leave the reactor continuously. Batch operation is also conceivable, although economically less relevant. According to one embodiment, the residence time of the pyrolysis vapors in the reaction chamber is 0.1 seconds to one minute, in particular 0.5 to 30 seconds, for example 1 to 10 seconds. The residence time can be adjusted by determining the pressure built up in the reactor and a correspondingly controlled outlet of the formed pyrolysis vapors from the reaction chamber.Thus, excessive fragmentation of the product compounds formed during reforming in the reactor can be prevented by excessively long residence times of the pyrolysis vapors.

[0018] In the context of this application, "arranged in the lower region of the reactor" means that the starting material in the pyrolysis reactor must have substantially passed through the reactor zone. In particular, this means that the pyrolysis vapors and pyrolysis gases must have completely passed through the first temperature level and substantially passed through the second temperature level. It goes without saying that the residence time specified in the application can only be achieved if the reactor geometry of the pyrolysis reactor is used sensibly. Therefore, the discharge device will frequently be arranged at the lower end of the reactor; the outlet for pyrolysis vapors and pyrolysis gases is therefore typically located at the lower end of the heating device arranged at the lowest point in the vertical direction (i.e.of the heating device for achieving the highest temperature level achieved), but at least not above the lower half in the vertical direction of this lowest heating device. If more than two heating devices arranged one above the other in the vertical direction are used, the outlet can in principle be arranged higher up, but in particular not above the lowest quarter of the heating areas formed in the vertical direction by the heating devices for forming the temperature levels. Accordingly, if heating is only provided by hot gas ducts or the like and / or only by heating lances, the outlet is not arranged above the lowest quarter in the vertical direction of such heating devices.For the sake of completeness, it should be noted that for the above definition of a heating system, only those heating systems are to be considered that can achieve the temperature of the first and / or second temperature level. At this point, it should be noted that it can certainly be sensible to thermally treat the bulk material in a vertical direction over a longer distance than the pyrolysis vapors. As already explained, a residence time that is too long can lead to excessive cracking of the pyrolysis vapors. With regard to the bulk material, however, a longer residence time can ensure that it is converted into higher-quality solids, for example because an even more complete recovery of pyrolysis gases and pyrolysis vapors is then possible, producing purer pyrolysis coke, which in turn can be used as a slow-release fertilizer in agriculture, etc.

[0019] As already explained, according to one embodiment, the temperature control or the selection of heating devices can be such that a temperature gradient develops in the bulk material. This temperature gradient can be adjusted vertically (depending on the orientation of the reactor) (for example, by heating devices in the form of gas channels in the vertical direction or by appropriately controlled heating devices).

[0020] By arranging a plurality of heating devices in a vertical direction, a plurality of different temperature levels can be realized, thus at least approximating a gradient. For example, reactors with 4, 5, 6, or more heating devices arranged one above the other in a vertical direction (above the outlet for pyrolysis vapors and pyrolysis gases) can be realized. The heating devices, for example, in a jacket shape, each have or provide temperature levels that increase from top to bottom, and the next higher temperature level is at least 50 °C higher than the previous level.A vertical gradient can also be realized by the aforementioned plurality of heating devices if the individual, for example jacket-shaped, heating devices themselves can each achieve a temperature level that increases from top to bottom (even then - with reference to the example given above - the then averaged temperature level of such heating devices is at least 50 °C higher than that of the previous level).

[0021] The temperature gradient can also be set additionally (or alternatively, if necessary) in a horizontal direction (i.e., in the direction of the reactor cross-section). This can be achieved, for example, by using large-diameter downcomers heated exclusively by heating devices located on the outside of the reactor, or by using heating devices arranged essentially vertically within the reactor, corresponding to the reactor geometry, with correspondingly large spacing between them. This creates a temperature gradient in a horizontal direction, especially with shorter residence times of the bulk material in the reactor.Typically, in the case of a horizontal temperature gradient, when heating is provided by only a few vertically stacked, for example, jacket-shaped heating devices, the temperature levels of the heating devices (above the outlet for pyrolysis vapors and pyrolysis gases) are further apart. For example, with only two of these heating devices, these can have or provide these temperature levels at a distance of 200 °C, for example, 450 °C and 650 °C. With three such heating devices, these can each be spaced apart by 150 °C, for example, so that the first temperature level is 350 °C and the second temperature level is 650 °C; between these two temperature levels, a further temperature level of 500 °C is then realized.

[0022] With such a horizontal temperature gradient, it is important to ensure that the temperature of the bulk material in the area where pyrolysis gases and vapors are separated from the pyrolysis coke (e.g., the lower end of a riser pipe used to separate gases and vapors) has reached at least the second temperature level. This can be determined, for example, using a temperature sensor located a few centimeters below the opening through which the separation takes place.

[0023] According to the application, it was found that in processes involving temperature gradients, the quality of the pyrolysis products formed is often better than in processes involving only two or three temperature levels. Without wishing to be limited to this, the inventors explain this by the gradual formation of the vapors (typically, cracking of the particularly easily broken chemical bonds occurs first; from temperatures of approximately 300 °C, decarboxylation, decarbonylation, and intermolecular dehydration then begin; from approximately 400 °C, the formation of more stable structures of the resulting molecules takes place; above 500 to 600 °C, aromatization, dimerization, and diene reactions, among others, begin).Accordingly, based on these theoretical considerations and explanations, and taking into account the relatively short residence times of the pyrolysis vapors, a first temperature level in the range of approximately 300 to 500 °C and—more importantly—a second temperature level above 500 °C (usually at least 100 °C higher), but especially in the range between 500 and 750 °C, should be particularly suitable for producing high-quality pyrolysis oils and a particularly efficient thermocatalytic reaction, even in arrangements without temperature gradients. Such high-quality pyrolysis oils are characterized in particular by a high proportion of aromatic hydrocarbons such as alkylbenzenes, naphthalenes, styrenes, or indoles. Aromatic hydrocarbons, and in particular alkylbenzenes, are desirable as antiknock agents in gasoline. Naphthalenes and indoles are also commercial fuel additives and have a positive effect on fuel quality.

[0024] Suitable starting materials or biomass in the feedstock include, in particular, cellulose-containing materials (especially wood residues, agricultural residues, and straw), industrial biomass residues (especially fermentation residues, brewer's spent grains, grape pomace, olive pomace, nutshells, or coffee residues), waste fats and animal fats not approved for human consumption or animal feed production, slurry from paper recycling, as well as liquid manure-containing materials and sewage sludge. It goes without saying that mixtures of these materials with one another can also be used as starting materials, or mixtures of the aforementioned materials with other biogenic substances. The starting material can, for example, have a water content of 5 to 30 wt.%, in particular 10 to 20 wt.%.

[0025] The most important advantage of the process according to the application is a complete simplification and thus reduction in cost of the existing thermocatalytic reforming (TCR) process. Instead of a screw reactor, a post-reformer, and a heating system distributed between both systems, an empty, externally heated (or internally heated) tube can be used. Pyrolysis and reforming take place in the same tube. The tube can be completely filled with the bulk material, thus allowing a higher throughput compared to the conventional process. To achieve higher throughputs or a larger fillable volume, the tube can also be easily extended vertically. There are essentially no other reactor components in the downcomer; therefore, blockage is unlikely. According to the application, the residence time of the solid in the tube can be controlled via a coke discharge screw.The discharge device (e.g., coke discharge screw) thus indirectly controls the transport of the bulk material through the reactor. However, it is only relevant for the removal, not for the actual movement of the bulk material through the reactor in a vertical direction. The process can be easily monitored based on the temperature distribution in the coke and the hydrogen concentration in the gas. Scale-up is also very simple; several tubes can be installed close together, integrated into a common heating jacket. Tube diameters should not exceed 500 mm - unless heating lances are used - otherwise, problems with heat transfer into the biomass may arise.

[0026] Initial tests on a laboratory plant initially showed that the resulting oils were of lower quality than those obtained using state-of-the-art TCR processes. However, the quality of the resulting oils could be improved by extending the tubular reactor, as this allows for longer heating of the biomass; alternatively, optimizing the temperature control in the reactor is also possible.

[0027] The present invention is a significant simplification of the thermocatalytic process according to the prior art. A clear characteristic or distinction between conventional pyrolysis oils and the reformed oils according to the application is the significantly higher product quality. In the case of the pyrolysis gases according to the application, this includes a very high hydrogen content (>20 wt%), while in the case of the oil according to the application, this includes a low polarity, a low acid number, and a low oxygen content in the oil (CHNO).

[0028] At this point, the parameter combination with which pyrolysis oils with a particularly good product quality are achieved should be summarized again: thermal treatment at a first temperature level of 300 to 500 °C, for example 350 to 450 °C and subsequently at a second temperature level of 550 °C to 750 °C which is at least 200 °C, in particular at least 250 °C higher than the first temperature level, in particular combined with pressures of 1.5 to 30 bar, for example 2.5 to 30 bar and in addition to these pressures or independently of these pressures with residence times of the pyrolysis vapors of 0.5 to 30 seconds, for example 1 to 10 seconds.

[0029] Like the TCR process, the process according to the application can also be carried out without the addition of a catalyst. The catalytic effect during reforming is therefore primarily achieved through the pyrolyzed solids formed.

[0030] The device according to the application for carrying out the method according to the application and initially the method itself are described in more detail below - without restricting generality - using an exemplary description and using different reactors and examples that can be used.

[0031] The application describes a process for producing high-quality products, namely pyrolysis oil, synthesis gas, and pyrolysis coke, for example for use as biochar, based on intermediate pyrolysis and a coupled reforming step. The process has been condensed so that pyrolysis and reforming can now be carried out in a single step. The feedstock used is biomass and biogenic residues and waste materials, which typically have a certain degree of granularity and a maximum water content of up to 30%; these can be contaminated with plastic or soil material up to 10-15%. The granularity ranges in particular from granular particles with an edge length of 2 mm to 40 mm. The starting material will often have an average particle size according to DIN 661 65 of 0.1 to 80 mm, in particular a particle size of 2 to 40 mm. A proportion of fine fraction as a dust load is acceptable up to approximately 10 wt.-% permissible (this proportion can be determined by sieve analysis, i.e. vibrating sieve analysis (tower / batch sieving) or air jet sieve analysis). In addition, an excessive fines fraction in the reactor could be detected by an (excessive) pressure drop. The system is arranged vertically in the manner of a heated downpipe. The biomass can be fed oxygen-free into a heated, vertical pipe using a stuffing screw or by pneumatic conveying via the lock. The feed is guided from top to bottom through the pipe by gravity. The residence time of the solids in the downpipe can be regulated by means of a discharge screw, which is flanged particularly at the bottom of the pipe and is cooled if necessary. The pyrolysis of the starting material or biomass now takes place in the downpipe; coke and pyrolysis vapors are produced.These migrate further down through the tube; the bulk material in the tube is heated, in particular by means of a temperature gradient, to a coke temperature or the highest temperature level achieved, which lies between 450 and 900 °C. Since hot pyrolysis coke is located in the lower part of the tube and the pyrolysis vapors are guided by the process in such a way that they are passed through the hot coke bed, reforming takes place simultaneously with pyrolysis in the same tube. The process runs in the absence of oxygen; it can be based in particular on intermediate pyrolysis, where residence times of the feedstock of 5 to 30 minutes of the solid in the tube must be achieved during the pyrolysis step. However, according to the application, the solid residence times are typically somewhat longer because, due to the single-stage process, reforming also takes place in the same reactor alongside pyrolysis.The downpipe can be heated externally electrically or by means of a hot gas heat exchanger. With regard to process temperatures, the downpipe can be heated from room temperature up to 750 °C or higher, from top to bottom with increasing temperature; the gradient can increase continuously. The pyrolysis gases are then extracted, particularly at the lower part of the downpipe, and fed to a fine dust filtration and condensation plant. An advantage of this arrangement compared to previous applications is the use of a tube as the reactor. In contrast to the screw reactors used in the TCR process, the tubular reactors according to the application are very robust against higher pressures. If a lock system is installed upstream and downstream of the tubular reactor on the inlet and outlet sides,downstream, the reactor can be operated in a pressure range of several bar, typically up to 30 bar, in particular up to 10 bar, for example also in a pressure range of more than 1.5 bar up to 5 bar, for example also in a pressure range of more than 2.5 bar. Better product qualities and yields can usually be achieved with higher pressures. In principle, with a correspondingly pressure-resistant design of the reactor, pressures of 200 bar and more can also be achieved, although from an economic point of view a design of the reactor for up to 30 bar is more advantageous. In principle, the process according to the application could also be carried out at pressures below normal pressure, for example at a pressure of a few mbar; here too, however, this is not advantageous from an economic point of view.

[0032] Higher pressures are particularly necessary when using very fine material, which would result in a high pressure drop in the post-reformer using the state-of-the-art TCR process. Thus, the present reactor can also process very fine biomass, which is more difficult in the case of the state-of-the-art TCR process.

[0033] In addition, a higher pressure is advantageous because it can usually significantly reduce the formation of long-chain hydrocarbons (especially tars).

[0034] Figure 1 shows a schematic representation of a downpipe reactor 1 in the "annular gap" variant. The downpipe reactor 1 is filled with bulk material up to a level L. Three heating devices 11, 12, and 13 are arranged vertically one above the other on the sides, of which at least the upper two heating devices 11, 12 serve to set the first and second temperature levels. Below the middle heating device 12 (which serves to set the second (i.e., the highest) temperature level in the bulk material) is the outlet 15 for pyrolysis gases and pyrolysis vapors. The outlet 15 is designed here as an annular gap; pyrolysis gases and pyrolysis vapors can be subsequently processed, for example, by condensation, dust separation (in a cyclone), and / or aerosol separation (using an electrostatic precipitator).At the lowest end of the reactor is the discharge device 18 for the pyrolysis coke; a screw conveyor is used here to control the residence time of the solids. At the upper end of the reactor is a feed device 8 for the feed material; this is equipped with a lock so that the reactor inlet can be sealed gas-tight on the side.

[0035] During operation, the reactor is therefore first filled with the starting material via the feed device 8 until the desired level L is reached. The temperature level of at least 300 °C is set by the uppermost heating device 11, and the second temperature level of at least 450 °C is set by the heating device 12. Typically, however, the second (i.e., the highest) temperature level (regardless of the selected reactor geometry) will have a temperature of at least 550 °C. The reactor can then be operated in batch mode or continuously, with starting material being added as required via the feed device 8. The starting material passes through the reaction chamber in a vertical direction essentially due to the force of gravity; moreover, the feed rate can also be controlled via the discharge speed via the discharge device 18.However, gravity alone is essential because "braking" via the discharge device 18 must not lead to a blockage of the reactor (a blockage would be detected in particular if no new starting material is fed in, especially because no release is made via a level sensor L, if present). The pyrolysis vapors and pyrolysis gases are discharged from the reactor via the annular gap-shaped outlet 15. To ensure a sufficient residence time, a lock or valve (not shown in Figure 1) is typically arranged downstream of the outlet 15.

[0036] Figure 2 shows a schematic representation of a downpipe reactor in the "riser pipe" variant, in which the gas outlet 15, unlike Figure 1, is not via an annular gap but via a riser pipe. It can be seen here that the lower end of the gas outlet 15 is located below the middle heating device 12 and extends into the area where the lowest heating device 13 is located. The possible position of multiple temperature sensors is not provided with reference symbols. The lowest heating device 13 serves solely to improve the coal quality of the produced pyrolysis coke, for which a long coal residence time is crucial. Accordingly, it is no longer used to set a temperature that—as in Fig. 1—is higher than the temperature level achieved by the heating device 12.

[0037] Figure 3 shows a schematic representation of a downpipe reactor 1 in the "flue gas ducts / lance" variant. This reactor type, in particular, allows for a large reactor diameter. The heating devices are not (or not only) located on the outer surface of the reactor, but also inside it. The heating devices 11, 12, 13 are designed here as flue gas ducts 14, with the flue gas flowing through the ducts from bottom to top, thus creating a temperature gradient in the reactor.The temperature is controlled in such a way that the flow velocity of the heating gas, in particular flue gas, is selected such that a temperature gradient is formed and the heating gas has at least the temperature of the second temperature level at the lower end of the flue gas ducts 14 and at most the temperature of the first temperature level at the upper end of the flue gas ducts 14 (whereby, regardless of the reactor geometries described in this section, the first temperature level is typically at least 50 °C lower than the second temperature level and usually also at least 100 °C lower). In most cases, the difference between the temperature levels is - as already explained above - more than 100 °C (in particular up to 300 °C). By way of example, a first temperature level is selected between 350 and 450 °C and a second temperature level is selected between 500 and 700 °C.Figure 3 also shows a design in which the outlet 15 for pyrolysis gases and pyrolysis vapors is arranged vertically at the very bottom of the reactor; specifically, the pyrolysis gases and pyrolysis vapors are only separated from the pyrolysis coke in the area of ​​the discharge screw 18.

[0038] Example: Pyrolysis and reforming of sewage sludge

[0039] Tests on the pyrolysis and reforming of sewage sludge were carried out in a reactor with a (vertical) length of 1.39 meters and a diameter of 0.27 meters, which was equipped with three equally long heating mats with a length of 40 cm arranged vertically one above the other as heating devices. The throughput of feedstock can be adjusted by timing the screw conveyor. The temperature control is selected so that the first temperature level is reached at the lower end of the upper heating mat and the second temperature level is reached on average at the lower end of the middle heating mat. The reactor is filled so that a volume up to a level L at just under 1.2 m is filled with bulk material, so that the upper end of the uppermost heating mat roughly corresponds to level L. This results in a bulk density of approximately 500 to 550 kg / m when using sewage sludge granules as the feedstock. 3achieved. Due to the pressure operation in combination with a possible pressure loss of up to almost 100%, the requirements for feedstock pretreatment can be reduced to a minimum, so that even difficult feedstocks can be used without compaction. At least in the area of ​​the lowest heating mat, the bulk material is essentially made up of pyrolysis coke. In the area of ​​the two upper heating mats, the pyrolysis gases and pyrolysis vapors generated during the combined pyrolysis / reforming process flow through the coke bed before being fed to the outlet for pyrolysis gases and pyrolysis vapors. Particularly important for improving the quality of pyrolysis gases and pyrolysis vapors is the reactor section, which is typically located in the lower area of ​​the second heating device and where the highest temperature level is achieved.The pyrolysis vapors can flow through a cyclone downstream of the outlet for dust removal and are subsequently cooled. Subsequently, oil and water are separated from the gas phase. To prevent oxygen from entering the system, the system can be continuously purged with a small amount of nitrogen if necessary.

[0040] Two test series, each with four sub-tests, are conducted. A reference test using the TCR process as described in WO2016 / 134794 A1 is carried out in such a way that the vertical "downpipe" reactor, as described above, is additionally preceded by a pyrolysis reactor operating at 450 °C. However, only one temperature level is achieved in the "downpipe" reactor, namely either 700 °C or, in one sub-test, 500 °C (these tests are referred to below as 2.1 to 2.4). The test series according to the claim does not have an upstream pyrolysis reactor; the temperature control via the heating mats is selected to create a temperature gradient between 250 to 300 °C and 500 to 700 °C (these tests are referred to below as 1.1 to 1.4).Each sub-test was conducted with a feed quantity of 150 kg of sewage sludge granules, which were purchased from the E&T Aichaberg sewage sludge dryer and had a bulk density of approximately 500 g / l. The sewage sludge granules used had a dry matter content of 31% carbon, 4.3% hydrogen, 4.4% total nitrogen, 1.2% sulfur, 18% oxygen, and an ash content (at 815 °C) of 41%. Mass spectrometry determined that they contained approximately 11–13% transition metals (mass percentages are given in each case). The total water content was between 5 and 10 mass percent. The sub-tests can be found in Table 1 below: Table 1.

[0041] Figure 4 shows the mass balances of the produced product spectrum. It can be seen that at (economically less relevant) slow throughput times, significantly more gas and significantly less oil are formed with the application-specific process (1.1 to 1.4) than with faster throughput times (and lower temperatures). However, compared to the TCR experiments (2.1 to 2.4), the oil content is significantly higher in the application-specific process.

[0042] Table 2 shows the parameters of the oil formed.

[0043] The measured values ​​were determined as follows:

[0044] Experiments 1.3, 1.4, 2.3 and 2.4:

[0045] - Water content according to DIN EN 14346: 2007-03

[0046] - Calorific value and heating value according to DIN CEN / TS 16023, DIN SPEC 19524: 2014-03

[0047] - Ash content according to DIN EN ISO 6245:2003-01

[0048] - Carbon content, nitrogen content and hydrogen content according to DIN 51732: 2014-07 -Oxygen content according to ASTM D5622 :2017

[0049] - Sulphur content according to DIN EN 14582: 2016-12

[0050] - Acid number (TAN) according to DIN EN 12634 : 1999

[0051] - dynamic viscosity according to DIN EN ISO 3219 : 1994 tests 1.1 , 1.2, 2.1 and 2.2:

[0052] - Water content according to DIN 51777

[0053] - Calorific value according to DIN 51900

[0054] - Carbon content, hydrogen content, nitrogen content and sulfur content according to DIN EN ISO 16948

[0055] - Acid number (TAN) according to ASTN D664

[0056] Table 2

[0057] It can be seen that the qualities of the oils formed with the partial tests according to the application (1 .x) are comparable with those obtained by means of the previously known TCR processes (partial tests 2.x).

[0058] Tab. 3 shows the gas composition of the formed gas

[0059] The contents were determined by gas chromatography.

[0060] The table shows that the hydrogen value decreases slightly with increasing throughput (both for the inventive experiments and the TCR experiments). The temperature in the reactor has a significant influence on the hydrogen value. In particular, the CO concentration decreases significantly at lower temperatures, while the CO2 concentration increases significantly. Regarding the formation of oils reformed under the present reaction conditions, it can be seen that with a longer residence time (= lower throughput) or higher temperature, better reforming occurs, and consequently more cracking occurs and the molecular length decreases.

[0061] In conclusion, it can be stated that the thermal treatment according to the application using the vertically oriented reactor, with a suitable adjustment of the residence time, particularly for vapors and gases (but also for solids), delivers product qualities and yields that can also be achieved using the state of the art (TCR process), albeit with a significant simplification of the process. This applies in particular if a sufficient temperature is introduced into the pyrolyzed starting material, which can be achieved particularly at higher temperatures during the thermal treatment and a sufficient residence time. However, for economic reasons, an extension of the residence time is less advantageous, so an extension of the (vertical) reactor or the thermal treatment zone within the reactor is an alternative.

Claims

Patent claims Process for producing pyrolysis oil, pyrolysis gas and pyrolysis coke with the following steps: A) providing a starting material comprising essentially biomass, in particular in lumpy form; B) feeding the starting material to a pyrolysis reactor having a substantially vertically arranged reactor chamber, wherein the reactor chamber is substantially tubular, in particular substantially cylindrical and / or substantially conical, wherein the starting material is fed in the upper region of the pyrolysis reactor, so that a bed of bulk material is present in the reaction chamber, which bed comprises the starting material to be pyrolyzed and optionally the pyrolysis coke; C) Thermal treatment of the starting material in the pyrolysis reactor essentially in the absence of oxygen by means of at least one heating device for the reactor chamber, wherein the pyrolysis coke, the pyrolysis gases and the pyrolysis vapors are formed from the starting material to be pyrolyzed and wherein the bulk material, the pyrolysis gases and the pyrolysis vapors are guided from top to bottom through the reaction chamber, wherein the movement of the bulk material through the reaction chamber is essentially caused by gravity and the movement of the pyrolysis gases and the pyrolysis vapors through the reaction chamber is essentially caused by gas pressure building up through the thermal treatment of the starting material and wherein the thermal treatment is carried out at least at a first temperature level of 300 to 650 °C, in particular 300 to 500 °C,for example 350 °C to 450 °C and subsequently at a second temperature level of 450 to 900 °C, preferably 500 to 750 °C, which is higher than the first temperature level, for example 550 °C to 650 °C, the residence time of the bulk material being 1 to 1200 minutes, in particular 3 to 600 minutes; D) Separation of the pyrolysis gases and pyrolysis vapors via an outlet located in the lower part of the pyrolysis reactor and separation of the pyrolysis coke via an outlet located in the lower part of the pyrolysis reactor Discharge device and optional provision of pyrolysis oil by partial condensation of the separated pyrolysis gas. Process according to the preceding claim, wherein a pressure-resistant reactor is used as the reactor for steps B) and C), and in particular the feeding in step B) takes place via a lock, in particular a lock closed on the inlet side, and optionally also the discharge of the pyrolysis coke in step D) takes place via a lock, in particular a lock closed on the outlet side. Process according to one of the preceding claims, wherein in step C) the residence time of the pyrolysis vapors in the reaction chamber is 0.1 seconds to one minute, in particular 0.5 to 30 seconds, for example 1 to 10 seconds. Process according to one of the preceding claims, wherein the difference between the first temperature level and the second temperature level is at least 100°C, in particular at least 200°C, for example at least 250°C.Method according to one of the preceding claims, wherein in step C) the at least one heating device is designed such that a plurality of temperature levels increasing from top to bottom can be formed, in particular such that a temperature gradient can be formed in the reaction chamber. Method according to one of the preceding claims, wherein the arrangement and design of the at least one heating device is selected such that a temperature gradient is formed in the reaction chamber in the horizontal direction. Method according to one of the two preceding claims, wherein the highest temperature level or the highest temperature of the temperature gradient formed in the reaction chamber is at least 650 °C. for example at least 700 °C, for example at least 750 °C or at least 900 °C.

8. Process according to one of the preceding claims, wherein the starting material is selected from fermentation residues, in particular from biogas and bioethanol processes, cellulosic materials, in particular wood residues, agricultural residues and straw, industrial biomass residues, in particular brewer's spent grains, grape pomace, olive pomace, nutshells or coffee residues, waste fats or animal fats, stillages from paper recycling, liquid manure-containing materials and sewage sludge or mixtures thereof.

9. Process according to one of the preceding claims, wherein the starting material consists of biomass or contains at least 85% by weight, in particular at least 90% by weight of biomass, wherein in addition to the biomass, the starting material may contain in particular plastics or earth material up to 10-15%.

10. Process according to one of the preceding claims, wherein the starting material provided has a water content of 5 to 30 wt.%, in particular of 10 to 20 wt.%. 1 1. Process according to one of the preceding claims, wherein the starting material provided is supplied in an average particle size according to DIN 661 65 of 0.1 to 80 mm, in particular in a particle size of 2 to 40 mm.

12. Process according to one of the preceding claims, wherein in step C) 1 kg to 3000 kg of starting material are passed through per hour, for example 1 kg to 500 kg per hour or 1500 to 3000 kg per hour.

13. Process according to one of the preceding claims, wherein a discharge screw for the pyrolysis coke is provided to regulate the residence time of the bulk material in the reactor. Method according to one of the preceding claims, wherein the heating in step C) is carried out via at least one heating device which surrounds the reaction chamber in a jacket-like manner and / or at least one heating lance in the interior of the reaction chamber. Method according to one of the preceding claims, wherein step C) is carried out in a reaction chamber, wherein the diameter of the reaction chamber 2 cm to 150 cm, in particular 5 cm to 50 cm. Method according to one of the two preceding claims, wherein Step C) is carried out in a reaction chamber with at least one heating lance inside the reaction chamber, the diameter of the reaction chamber being 50 cm to 150 cm. The process according to any one of the preceding claims, wherein steps B) and C) are carried out in a plurality of similar pyrolysis reactors according to the preceding claims, in particular 3, 4, 5, 6, or 7 pyrolysis reactors, the thermal treatment according to step C) being carried out via a common heating device in at least some of the plurality of pyrolysis reactors. A pyrolysis reactor for carrying out the process according to any one of the preceding claims.

Images