FAST PYROLYSIS REACTOR FOR ORGANIC BIOMASS MATERIALS WITH AGAINST FLOW INJECTION OF HOT GASES

Abstract

The main purpose of the invention is a fast pyrolysis reactor (1) with entrained flow of biomass organic particles (2), comprising a reaction chamber (3), a device (4) for injection of particles (2) in the upper part (3a) of the reaction chamber (3), to form a flow (FG) of particles (2) dropping by gravity, an evacuation duct (5) for products originating from the pyrolysis reaction present in the reaction chamber (3), characterized in that it also comprises a counter current hot neutral gases injection duct 6 in the lower part (3b) of the reaction chamber (3) making it possible to form a counter current flow (FG) of hot neutral gases coming into contact with the flow (FG) of particles (2) dropping by gravity, the temperature of the hot neutral gases being between 500 and 600 C., and the diameter of the particles (2) being between 200 m and 1 mm.

Claims

1-16. (canceled)

17. A fast pyrolysis reactor with an entrained flow of biomass organic particles, the fast pyrolysis reactor comprising: a tubular reaction chamber in which a pyrolysis reaction of particles takes place, comprising an upper part and a lower part opposite the upper part, a device for injection of particles in the upper part of the tubular reaction chamber, to form a flow of particles dropping by gravity in the tubular reaction chamber, an evacuation duct for products, comprising gases and pyrolyzed particles, originating from the pyrolysis reaction and present in the tubular reaction chamber, and a counter current hot neutral gases injection duct in the lower part of the tubular reaction chamber to form a counter current flow of hot neutral gases coming into contact with the flow of particles dropping by gravity, so as to generate a fast pyrolysis reaction of the particles, a temperature of the hot neutral gases being between 500 and 600 C., and a diameter of the particles being between 200 m and 1 mm.

18. The fast pyrolysis reactor according to claim 17, wherein the evacuation duct opens up in the upper part of the tubular reaction chamber to evacuate products derived from the pyrolysis reaction in the tubular reaction chamber, since the products migrate to the upper part of the tubular reaction chamber.

19. The fast pyrolysis reactor according to claim 17, wherein the diameter of the particles is between 200 m and 800 m.

20. The fast pyrolysis reactor according to claim 17, wherein the device for injection of particles comprises: a reservoir of particles, comprising particles and located outside the tubular reaction chamber, a tubular injector of particles located in the upper part of the tubular reaction chamber, and means of transporting particles originating from the reservoir to the tubular injector.

21. The fast pyrolysis reactor according to claim 20, wherein a diameter of the tubular injector is less than a diameter of the tubular reaction chamber.

22. The fast pyrolysis reactor according to claim 20, wherein the means of transporting the particles comprise a worm screw system or a vibrating belt system.

23. The fast pyrolysis reactor according to claim 17, further comprising: means of injecting an entrainment gas in the upper part of the tubular reaction chamber, to improve the injection of particles into the tubular reaction chamber.

24. An installation for fast pyrolysis of biomass organic particles, comprising: the fast pyrolysis reactor according to claim 17, a burner upstream from the fast pyrolysis reactor, configured to produce hot neutral gases circulating in the counter current hot neutral gases injection duct, a separator downstream from the fast pyrolysis reactor, configured to enable separation of pyrolytic coke and a flow of condensable and incondensable gases, and a condenser downstream from the separator, configured to enable separation of pyrolytic oil and the flow of incondensable gases.

25. The installation according to claim 24, further comprising: means of injection of a first part of an incondensable gases flow output from the condenser into a boiler after heating by combustion of the first part of the incondensable gases flow.

26. The installation according to claim 24, further comprising: means of injecting a second part of an incondensable gases flow output from the condenser to a heat exchanger of the burner to form the hot neutral gases circulating in the counter current hot neutral gases injection duct, heat being produced from the burner supplied by a first part of the incondensable gases flow.

27. A process for fast pyrolysis of biomass organic particles in the fast pyrolysis reactor according to claim 17, the process comprising: counter current injecting hot neutral gases into the tubular reaction chamber of the fast pyrolysis reactor in a direction opposite to a direction of particles dropping by gravity, on which the fast pyrolysis reaction takes place.

28. The process according to claim 27, further comprising: heating hot neutral gases circulating in the counter current hot neutral gases injection duct and/or forming the hot neutral gases circulating in the counter current hot neutral gases injection duct, with an incondensable gases output from the condenser, wherein the process is implemented with a fast pyrolysis installation and the fast pyrolysis installation comprises: the fast pyrolysis reactor; a burner upstream from the fast pyrolysis reactor, configured to produce hot neutral gasses circulating in the counter current hot neutral gases injection duct, a separator downstream from the fast pyrolysis reactor, configured to enable separation of pyrolytic coke and a flow of condensable and incondensable gases; and a condenser downstream from the separator, configured to enable separation of pyrolytic oil and the flow of incondensable gases.

29. The process according to claim 27, further comprising: injecting an entrainment gas into the tubular reaction chamber of the fast pyrolysis reactor, to improve injection of particles into the tubular reaction chamber.

30. The process according to claim 27, further comprising: adding heat with pyrolytic coke as fuel.

31. The process according to claim 27, further comprising: placing a heat exchanger between the separator and the condenser to enable heat recovery.

32. The process according to claim 27, further comprising: producing a fuel with pyrolytic coke mixed with pyrolytic oil.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The invention can be better understand by reading the following detailed description of a non-limitative example embodiment of the invention, and an examination of the diagrammatic and partial figures in the appended drawing on which:

[0051] FIG. 1 shows a diagram illustrating an example fast pyrolysis reactor according to the invention,

[0052] FIG. 2 illustrates the size grading of particles used in the reactor in FIG. 1 in graphic form, with a Rosin-Rammler type of distribution representing the percentage of particles as a function of their diameter,

[0053] FIGS. 3A, 3B and 3C illustrate the trajectory of biomass particles, the gas temperature and the molar fraction of water vapor in the reaction chamber respectively, for a first configuration of the reactor in FIG. 1,

[0054] Ia FIG. 4 represents the change in the fraction by mass of non-pyrolyzed dry material in the particles in a first configuration the reactor in FIG. 1, as a function of time,

[0055] FIGS. 5A, 5B and 5C illustrate the trajectory of biomass particles, the gas temperature and the molar fraction of water vapor in the reaction chamber respectively, for a second configuration of the reactor in FIG. 1,

[0056] Ia FIG. 6 represents the change in the fraction by mass of non-pyrolyzed dry material in the particles in a second configuration the reactor in FIG. 1, as a function of time,

[0057] FIG. 7 shows a diagram illustrating an example fast pyrolysis installation according to the invention, comprising the fast pyrolysis reactor in FIG. 1.

[0058] In all these figures, identical references can designate identical or similar elements.

[0059] Furthermore, the different parts shown on the figures are not necessarily all at the same scale, to make the figures more easily understandable.

DETAILED PRESENTATION OF A PARTICULAR EMBODIMENT

[0060] Note that throughout the description, the terms upper and lower should be considered relative to the vertical direction, the direction along which particles drop under the effect of the earth's gravity. In particular, the upper part of the reaction chamber is located above the lower part of the reaction chamber. In other words, the upper part is the top part of the chamber, and the lower part is the bottom part of the chamber. Moreover, the terms upstream and downstream should be considered relative to the normal flow direction of the flow considered (from upstream to downstream), in particular the gas flow and/or particles flow.

[0061] With reference to FIG. 1, the figure diagrammatically shows an example embodiment of a reactor 1 according to the invention for fast pyrolysis of biomass organic particles 2.

[0062] The biomass organic particles 2 may be of any type, they may be made of organic materials with plant, animal and/or fungal origin. They may be in the form of a powder of biomass particles 2.

[0063] Thus, the reactor 1 comprises firstly a tubular reaction chamber 3 in which the pyrolysis reaction of particles 2 occurs.

[0064] This reaction chamber 3 is formed from a main cylindrical body 3c at the ends of which are the upper part 3a and the lower part 3b of the reaction chamber 3. These upper 3a and lower 3b parts have a tapered shape. However, the invention is not limited to this type of shape. As a variant, the upper 3a and lower 3b parts may have a cylindrical shape, particularly they may have the same diameter as the main cylindrical body 3c.

[0065] Furthermore, the reactor 1 comprises a device 4 for injection of particles 2 into the upper part 3a of the reaction chamber 3.

[0066] This injection device 4 comprises a reservoir 4a or hopper 4a of particles 2, containing particles 2 on which the pyrolysis reaction will be carried out in the reaction chamber 3. This reservoir 4a is located outside the reaction chamber 3.

[0067] The injection chamber 4 also comprises a tubular injector 4c injecting particles 2 into the reaction chamber 3, enabling injection of a stable and known flow of particles 2.

[0068] This tubular injector 4c is located in the upper part 3a of the reaction chamber 3. It is present near the top, followed by a cylindrical shape in the lower part in which particles 2 are ejected. The diameter Di of the cylindrical part of the tubular injector 4c is advantageously less than the diameter Dr of the cylindrical body 3c of the reaction chamber 3. The outlet nozzle of the tubular injector 4c may advantageously be fitted with a particle detector enabling a wider distribution of particles in the reactor. Furthermore, the useful height of the reaction chamber 3 is defined so as to achieve a sufficiently long drop time of the particles 2 for the pyrolysis reaction on them to be completed.

[0069] Moreover, the injection device 4 comprises transport means 4b for particles 2 output from the reservoir 4a to the tubular injector 4c, external to the reaction chamber 3. These transport means 4b may be of any type. In the example shown, they consist of a worm screw. As a variant, they could also be formed for example from a vibrating belt.

[0070] The injection of particles 2 through the injection device 4 into the reaction chamber 3 can then form a flow of particles 2 dropping by gravity FG into the reaction chamber 4, so as to allow the particles 2 to pass through an upper part of the reaction chamber 3 and before its lower part 3b.

[0071] When the particles 2 are injected into the tubular injector 4c, injection means N of an entrainment gas, for example nitrogen, are placed in the tubular injector 4c of the injection device 4 so as to improve and aid the injection of particles 2 into the reaction chamber 3. The injection of such a neutral entrainment gas also inerts the distribution of particles 2 towards the reaction chamber 3 and thus prevents return of pyrolysis gas to the injection device 4.

[0072] Furthermore, the reactor 1 also comprises an evacuation duct 5 opening up in the upper part 3a of the reaction chamber 3 through which products derived from the pyrolysis reaction in the reaction chamber 3 can be evacuated, these products being entrained towards the upper part 3a of the reaction chamber 3 and containing gases, forming a flow of condensable and incondensable gases FR and pyrolyzed particles 2 that will form pyrolytic oil, incondensable gases and pyrolytic coke called char, respectively.

[0073] Moreover, the reactor 1 also comprises a hot neutral gases counter current injection duct 6 in the lower part 3b of the reaction chamber 3, to obtain a fast pyrolysis reaction with entrained counter-current flow.

[0074] This counter current injection duct 6 makes it possible to form a counter current flow FC of hot neutral gases coming into contact with the flow of particles 2 dropping by gravity FG, so as to generate the fast pyrolysis reaction of the particles 2.

[0075] The temperature of these hot neutral gases forming the counter current flow FC is preferably between 500 and 600 C., while the diameter of the particles 2 contained in the flow of particles 2 dropping by gravity FG is preferably between 200 m and 1 mm, advantageously between 200 m and 800 m.

[0076] The flow of hot gases forming the counter current flow FC and the diameter Dr of the main body 3c of the reaction chamber 3 are calculated such that the velocity of hot gases is high enough to entrain pyrolyzed particles 2 to the upper part 3a of the reaction chamber 3.

[0077] The pyrolysis reaction inside the reaction chamber 3 takes place as described below. When the particles 2 in the flow FG dropping by gravity meet the hot gases in counter current flow FC, these particles 2 are heated and lose their residual water. The pyrolysis reaction starts when the particles 2 reach a temperature of about 300 C. The particles 2 then continue to be heated until they come into temperature equilibrium with the hot gases that are cooled. Starting at the beginning of the pyrolysis reaction, the particles 2 release condensable and incondensable gases forming the gas flow FR. The particles 2 thus lose a large proportion of their volume and their mass, particularly of the order of 85% at a temperature of about 500 C. to 550 C., 70% of the mass being converted into condensable gases that will form pyrolysis oil and 15% into incondensable gases. The particle density 2 then becomes low and starting from a given flow of hot gases, the then pyrolyzed particles 2 are entrained towards the top of the reactor 1 in its upper part 3a with the flow of condensable and incondensable gases FR to be evacuated through the evacuation duct 5.

[0078] For example, with a reaction chamber 3 comprising a main body 3c with diameter Dr equal to about 20 cm and height Hr equal to about 3.6 m, a flow of biomass particles 2 equal to about 10 kg/h and a flow of hot gases in the counter current flow FC of the order of 80 Nm.sup.3/h, the velocity of hot gases obtained is of the order of 2 m/s such that almost 95% of particles 2 with a diameter of between 0.1 and 1 mm, are pyrolyzed.

[0079] Different simulations were made using the Fluent fluid dynamics simulation software to evaluate operation of the fast pyrolysis reactor 1 according to the invention.

[0080] We thus considered a biomass particles flow 2 of the order of 10 kg/h, these particles 2 being wood particles with a moisture content of 7% and having a Rosin-Rammler distribution type of size grading relative to the diameter Dp of the particles 2, represented on FIG. 2. These particles 2 thus have an average diameter of the order of 0.500 mm, a minimum diameter of the order of 0.350 mm and a maximum diameter of the order of 1 mm.

[0081] Moreover, it was considered that the reaction chamber 3 comprises a main body 3c with diameter Dr of the order of 20 cm, its walls being adiabatic. The diameter Di of the tubular injector 4c is of the order of 5 cm.

[0082] The biomass particles 2 are also injected using an entrainment gas in the form of nitrogen at a velocity of the order of 0.1 m/s and at a temperature of about 27 C. The counter current flow FC comprises nitrogen injected at about 550 C.

[0083] Two configurations were simulated and optimized as a function of the height Hr of the main body 3c of the reaction chamber 3 and the injection velocity of the counter current flow FC.

First Configuration

[0084] In the first configuration, the height Hr of the main body 3c of the reaction chamber 3 is 3.6 m, while the injection velocity of the counter current flow FC is 1 m/s.

[0085] Two indicators are defined to quantify the performance of the reactor 1: [0086] the pyrolysis ratio .sub.p that is the ratio between the mass flow of pyrolysis products obtained and the mass flow of injected dry biomass particles, namely: [0087] .sub.p=[mass flow of pyrolysis products obtained/mass flow of injected biomass particles], [0088] the yield r.sub.g of uncracked tars that is the ratio between the flow of uncracked tars obtained and the flow of tars obtained ideally with complete hydrolysis in the absence of cracking, namely: [0089] r.sub.g=[flow of uncracked tars obtained/flow of tars obtained ideally with a complete hydrolysis in the absence of cracking].

[0090] Thus, in this first configuration with injection of the counter current flow FC at 1 m/s and height Hr of the main body 3c of the reaction chamber 3 equal to 3.6 m, the biomass particles 2 are pyrolyzed with a ratio .sub.p equal to 99%, while the yield of uncracked tars r.sub.g is 98%.

[0091] Thus, pyrolysis is practically complete and the yield of uncracked tars is very close to maximum, since the cracking rate is low. This means that the primary tars exit from the reactor 1 unchanged and can therefore be recovered, namely condensed, in the form of pyrolytic oil.

[0092] FIGS. 3A, 3B and 3C illustrate the trajectory of biomass particles, the gas temperature expressed in Kelvin (K) and the molar fraction of water vapor in the reaction chamber 3 respectively, in the reactor 1, Furthermore, FIG. 4 represents the change in the mass fraction Fm of non-pyrolyzed dry material in the particles 2, as a function of the time t expressed in seconds.

[0093] It is thus observed that practically all the particles 2, after drying and pyrolysis, are evacuated through the top of the reaction chamber 3 in the form of char. Only the largest particles 2 do not rise and stay at the bottom of the chamber 3 with less complete pyrolysis. Thus, 93% of the outlet mass of the particles is evacuated from the top, the remaining 7% being collected at the bottom. Moreover, the cold zone of the reaction chamber 3 is located at the top of the chamber. Furthermore, water vapor rises immediately after it is produced by the particles 2.

[0094] Furthermore, the height Hr of 3.60 m has been optimized for an injection velocity of the counter current flow FC equal to 1 m/s. This means that the yield of the reactor 1 cannot be improved by increasing the height. Conversely, a lower height would reduce this yield.

Second Configuration

[0095] In the second configuration, the height Hr of the main body 3c of the reaction chamber 3 is 3 m, while the injection velocity of the counter current flow FC is 1.5 m/s.

[0096] FIGS. 5A, 5B and 5C illustrate the trajectory of biomass particles, the gas temperature expressed in Kelvin (K) and the molar fraction of water vapor in the reaction chamber 3 respectively, in the reactor 1, Furthermore, FIG. 6 represents the change in the mass fraction Fm of non-pyrolyzed dry material in the particles 2, as a function of the time t; expressed in seconds.

[0097] We thus observed that increasing the injection velocity of the counter current flow FC to 1.5 m/s has two advantages: with an injection velocity of 1.5 m/s, all particles 2 exit through the top of the reaction chamber 3 except for a very small proportion;

[0098] moreover, the height of the optimized reaction chamber 3 is modified to 3 m. On the other hand, the performance of the reactor 1 is not as good since the pyrolysis ratio .sub.p is 88% and the yield r.sub.g of uncracked tars is 87%.

[0099] We will now refer to FIG. 7 to describe an installation 10 for fast pyrolysis of biomass organic particles 2 comprising a fast pyrolysis reactor 1 like that described previously with reference to FIG. 1.

[0100] As can be seen on this FIG. 7, in addition to the reactor 1, the installation 10 comprises a burner 11 including a heat exchanger E located upstream from the reactor 1 and configured to produce hot gases forming the counter current flow FC circulating in the hot gases counter current injection duct 6.

[0101] Furthermore, the installation 10 comprises a separator 12 (or cyclone) forming a filtration device, placed downstream from the reactor 1 and configured to enable the separation of pyrolytic coke C, or char C, by filtration at a temperature higher than 250 C., and a condensable and incondensable gases flow FR starting from products originating from the pyrolysis reaction in the reaction chamber 3, including a condensable and incondensable gases flow FR at temperature TR of the order of 400 C. and pyrolyzed particles 2.

[0102] Furthermore, the installation 10 also comprises a condenser 14 placed downstream from the separator 12 and configured to enable the production of pyrolytic oil H and an incondensable gases flow FR starting from the condensable and incondensable gas flow FR output from the separator 12. The temperature in this condenser 14 is preferably as low as possible, particularly of the order of 0 C. for an industrial process.

[0103] Advantageously, the installation includes energy integration of the incondensable gases flow FR with the formation of a closed circuit to improve the performance of the fast pyrolysis process.

[0104] In particular, the installation 10 comprises injection means in the form of a first circulating pump Ci.sub.1 to inject a first part FR.sub.1 of the incondensable gases flow FR output from the condenser 14 to the burner 11 after this first part FR.sub.1 has been heated by combustion of these incondensable gases mixed with an air flow A. Methane M is preferably used to for preheating during startup phases or as makeup to maintain the temperature. Note that a single circulation pump can also be used for the two lines FR.sub.1 and FR.sub.2, with a regulation valve on each line to adjust the corresponding flows.

[0105] The installation 10 also comprises injection means in the form of a second circulating pump Ci.sub.2 so that a second part FR.sub.2 of the incondensable gases flow FR output from the condenser 14 to the heat exchanger E of the burner 11 can be injected to form the counter current flow FC of hot gases circulating in the hot gases counter current injection duct 6.

[0106] More particularly, the burner 11, more precisely the chamber in which the burner 11 is placed, comprises a heat exchanger E in which the second part FR.sub.2 of the incondensable gases flow FR circulates, this flow being heated by the first part FR.sub.1 of the incondensable gases flow FR, itself heated by its combustion with the flow of air and methane M. After passing in the burner 11, this first part of the incondensable gases flow FR.sub.1 is evacuated in the form of exhaust gases through the outlet EF from the burner 11 after having transferred its heat to the incondensable gases flow FR.sub.2 by means of the heat exchanger.

[0107] The use of incondensable gases FR at the burner 11 is advantageous to the extent that calculations show that the energy contained in these incondensable gases is of the order of 8 MJ/Nm.sup.3, which is enough to provide the necessary heat to the reactor 1. Nevertheless, external gas and particularly natural gas or another type of combustible gas can be added to the burner to achieve a certain margin on the power.

[0108] Obviously, the invention is not limited to the example embodiment that has just been described. An expert in the subject can make various modifications to it.

[0109] In particular, it would be possible to recover char C from the separator 12 and the burner, for example by means of the flow of air A and methane M, to inject it also into the burner 11 and add additional heat to the reactor 1.

[0110] A heat exchanger can also be placed at the horn, in other words between the separator 12 and the condenser 14, to recover heat and use it to preheat the counter current flow FC of hot gases before it enters the reaction chamber 3.

[0111] Furthermore, the char C and the pyrolysis oil H obtained can be mixed to form a slurry with a better calorific value in combustion than pyrolysis oil alone.