FR3043091A1 - THERMOLYSIS DEVICE WITH FRAGMENTATION MECHANISM - Google Patents

Abstract

Thermolysis device (1) comprising, on the one hand, an enclosure (2), comprising at least one input of particles of raw material (4), at least one output of treated products (5) and at least one outlet of gaseous products ( 6), on the other hand a caloric supply means (7) arranged in such a way as to regulate the temperature inside said enclosure (2), an internal axis (3) placed inside said enclosure ( 2), characterized in that said inner axis (3) and said enclosure (2) are rotatably mounted relative to each other and in that said enclosure (2) is divided into at least two portions communicating between they via at least one gap (8) delimited by a first mechanical element (30), fixed on said inner shaft (3), and a second mechanical element (20), fixed on the inner face (21) of said enclosure (2). ), the local width of said gap varying between a maximum value (81) and a minimum value (82) as a function of the relative position of the inner axis (3) relative to said enclosure (2).

Description

Field of the invention

The present invention belongs to the field of energy production by gasification of solid or liquid organic material, this material may be derived from biomass, organic waste or fossil resources. The invention particularly relates to a thermolysis device but also to a process for producing synthesis gas from organic material using said device.

State of the art

The gasification of organic matter is one of the possible routes for its energy recovery, the other routes being combustion and methanation.

The organic matter is always predominantly composed of molecules composed of Carbon C, Hydrogen H and Oxygen 0, optionally combined with water H 2 O. If this organic material is subjected to a temperature of more than 150 ° C in oxygen deficiency, it undergoes a so-called pyrolysis transformation which breaks the carbon molecules by breaking covalent bonds. The products obtained during this pyrolysis are solids (mineral ash plus residual carbon called Char), vapors that condense at ambient temperature and pressure (tars, oils) and synthesis gases, also called syngas, which remain in state. gaseous at ambient temperature and pressure (carbon monoxide, dihydrogen and gaseous elements that are economically undervaluable, such as carbon dioxide).

The char produced by the pyrolysis also undergoes carbonation by association of the carbon with oxygen, said oxygen coming in part from the molecules of the original organic material, and hydrogen which produces carbon monoxide, dihydrogen and hydrogen. Methane in ideal conditions. This reaction is endothermic and requires a specific heat input. Traditionally, this contribution is ensured by an air combustion reaction carried out in the process.

According to the current state of the art of gasification processes of organic matter, the production of syngas uses mainly two technologies: - In a fixed-bed process of co-current or countercurrent type, with so-called slow pyrolysis the raw material is introduced into an enclosure in which it undergoes the pyrolysis and gasification steps during its displacement. Air is introduced locally into the enclosure to allow partial combustion of the tank and generate the energy required for endothermic gasification. The gases produced are extracted either from the input side of the raw material (countercurrent logic) or from the ash outlet side (co-current logic). - In a so-called pyrolysis fluidized type so-called rapid process, the raw material is previously finely ground and then introduced into a reactor where a mass of very hot particles agitates, for example dolomite sand. The raw material powder then undergoes almost instantaneously the steps of pyrolysis and then gasification. The gases produced are collected in a single main outlet placed in the upper position. The next step separates the gases produced from the sand. This is then recirculated to the reactor to be recycled in the case of circulating fluidized beds.

These traditional solutions have the following defects in particular: - In the case of the fluidized bed, the raw material must be carefully calibrated in order to distribute itself rapidly in the sand bed. To this end, a complex grinding and calibration of incoming equipment is required. The sand bed is maintained in a state of bubbling which implies a perfect fluidity of the sand, and any initiation of ash melting within the sand bed greatly compromises the efficiency of the process. For these reasons, fluidized bed processes are operated at temperatures generally below 900 ° C, and the presence of alkalis such as potassium must be very limited. However, a temperature of 900 ° C, on the one hand, involves the residual presence of aromatic polycyclic hydrocarbons (tars) and, on the other hand, does not allow to ensure the total gasification of the tank.

In the case of the fixed bed, the raw material descends by gravity while the gases must circulate within it. It is then necessary not to introduce fine particles or too small, typically less than 1 mm in diameter, as this could block the homogeneous circulation of gases in the bed. The raw material is therefore screened in order to reject the fine particles before it is introduced into the pyrolysis reactor. Whatever the precautions taken, preferential currents are inevitable with a risk of collapse of the bed. For these reasons, the co-current fixed beds are limited to small powers (less than 2 MW) and the fixed beds against the current do not allow operation of the syngas in engine or turbine because of insufficient gas quality . In both cases, the reaction which takes place first is pyrolysis because the energy required for the transformation of the raw material is provided by a combustion carried out in the same device so that the heat is immediately available. The defect of such an arrangement is that the combustion generates the appearance of undesirable elements such as nitrogen oxides which are then mixed with the syngas at the expense of its quality. On the other hand, it is not possible to recover the thermal energy of the gases leaving the equipment in order to supply the gasification process, which induces a yield loss which generally exceeds 10%. Old solutions, which are only little used to date, implement a mixing of raw material in a fixed or rotating drum to ensure homogenization and advancement of products from an entry to an exit. Some brewing accessories are present in the apparatus, but the lack of these solutions is that no specific mechanical action is provided during the work to facilitate the release of vapors during pyrolysis. In addition, operating temperatures are generally below 600 ° C, not allowing the production of syngas of sufficient quality for operation in an engine or turbine.

Description of the invention

The present invention aims to overcome the drawbacks of the state of the art by providing a thermolysis device capable of producing char and syngas of much better quality than that obtained with pyrolysis while using a less expensive technology than the traditional solutions.

Thus, the present invention relates to a thermolysis device comprising on the one hand an enclosure, comprising at least one input of particles of raw material, at least one outlet of treated products and at least one outlet of gaseous products, on the other hand a caloric intake means arranged in such a way as to regulate the temperature inside said enclosure, an internal axis placed inside said enclosure, characterized in that said inner shaft and said enclosure are rotatably mounted one relative to the other and in that said enclosure is divided into at least two portions communicating with each other via at least one gap delimited by a first mechanical element, fixed on said inner axis, and a second mechanical element, fixed on the face interior of said chamber, the local width of said gap varying between a maximum value and a minimum value depending on the relative position of the inner axis by ra port to said enclosure.

According to a preferred embodiment of the invention, said gap has a minimum width of 2 mm.

According to a preferred embodiment of the invention, said enclosure is rotatably mounted about said inner axis.

According to a preferred embodiment of the invention, said inner shaft is rotatably mounted about its longitudinal axis.

According to a preferred embodiment of the invention, said device further comprises a speed regulating means for adjusting the mechanical torque of the relative movement between said chamber and said internal axis.

According to a preferred embodiment of the invention, the average vector normal to the faces delimiting the gap has a direction inscribed in a cone of angle less than 30 ° with respect to the radial direction of the geometry of revolution of the axis. inside. Most preferably, said first and second mechanical elements respectively have the shape of a cam and a contrecam.

According to another preferred embodiment of the invention, the normal mean vector to the surfaces delimiting the gap has a direction inscribed in a cone of angle less than 45 ° with respect to the axial direction of the geometry of revolution of the axis. inside. Most preferably, said first and second mechanical elements are respectively in the form of a finger and a counter-finger having bevelled faces delimiting said gap.

According to a preferred embodiment of the invention, said first and / or second mechanical elements consist of a material having a thermal conductivity greater than 50 W / mK.

According to a preferred embodiment of the invention, at least one of the first and / or second mechanical elements is equipped with a caloric supply means by electric or heat transfer fluid effect.

According to a preferred embodiment of the invention, said device comprises at least one axial transfer means disposed inside said enclosure. Even more preferably, said axial transfer means comprises one or more spiral portions.

According to a preferred embodiment of the invention, the axis passing through said input of raw material particles and said output of treated products is inclined at a maximum inclination of 45 ° with respect to the horizontal.

According to a preferred embodiment of the invention, said device comprises a plurality of caloric supply means each associated with a temperature control means defining zones having independent temperature regimes within said enclosure. Most preferably, said device comprises at least one gas outlet per zone of said enclosure.

The invention also relates to a method of thermolysis of organic material implementing a device according to the invention.

According to a preferred embodiment of the invention, said enclosure is placed in a confined atmosphere. The advantage of the invention is first that the raw material undergoes, in a chamber generally sealed to the outside atmosphere, a progressive thermolysis transformation associated with a mechanism of fragmentation of the friable surface of the treated material.

The installed mechanism makes it possible, effectively and economically, to unhook the material made friable on the surface, to reduce it to calibrated dust to promote the vaporization of gases and oils, to quickly expose the new material to heat thus facilitating its thermolysis, to transport the resulting tank to its exit point and collect the different vaporized fluids to their own exit points. In particular, this invention makes it possible to use a raw material of coarse size having a wide particle size distribution, of which more than 90% of the mass consists of elements having a maximum size of between 50 cm and 1 mm. Other characteristics and advantages of the invention will emerge from the following detailed description of the non-limiting embodiments of the invention, with reference to the appended figures, in which: FIG. 1 schematically represents the thermolysis device 1 according to FIG. invention and its general principle of operation. FIG. 2 diagrammatically represents an example of an axial air gap used according to a variant of the invention. FIG. 3 diagrammatically represents an example of a radial air gap used according to a variant of the invention. FIG. 4 schematically represents the principle of the axial air gap used according to a variant of the invention. FIG. 5 diagrammatically represents the principle of the radial air gap used according to a variant of the invention.

Presentation of an embodiment

By convention we will denote by the word thermolysis 11 together the steps of separation of the volatile elements from the carbon chains (including water) and the reduction of the length of these carbon chains to obtain pure carbon called char and ash on one side and different reaction gases including volatile compounds, dihydrogen, methane and carbon monoxide on the other side.

Pyrolysis is said to be autothermic, the thermal energy being provided by the partial combustion of a portion of the entrants by a sub-stoichiometric supply of external oxygen.

When the reaction is allothermic, that is to say provided by external thermal energy, and therefore without significant recourse to internal combustion of a portion of the entrants, the term thermolysis will be used. The invention relates to this thermolysis step which is characterized by a separation of the constituent elements of the organic material treated under the effect of a high temperature, between 80 ° C and 700 ° C, and lack of oxidizing agent such as 1'oxygène. The lack means that the amount of available oxidant is much less than the amount required to allow a complete oxidation reaction ie stoichiometric total combustion.

As represented in FIG. 1, the present invention relates to a device 1 for thermolysis of organic material consisting of an enclosure 2, preferably fixed and of cylindrical shape.

An inner shaft 3 is placed inside the enclosure, guided by any conventional mechanical means such as bearings connecting to the enclosure 2. The mechanism may also be cantilevered. The rotation guide of the inner axis 3 is preferably designed in a sealed manner with respect to the enclosure 2 in order to prevent outside air from entering the enclosure by this way, thus calling into question the search for a lack oxidant.

A raw material feed 4 is installed at one end of the enclosure. This supply 4 is designed in a sealed manner in order to prevent outside air from entering the enclosure by this way, thus calling into question the search for a lack of oxidant. Any traditional solution of waterproof supply of material is suitable. For example, an airlock system with two alternately controlled dry valves makes it possible to deliver regularly in the enclosure connected to the airlock a quantity of material defined by the volume of the airlock. Another example is obtained with the use of a hopper and a rotary lock. At each rotation of the lock, a dose is delivered to the enclosure.

An outlet of solid products from the raw material processing is installed at the other end of the enclosure. The tightness of this connection can be obtained by the use of a two-valve lock, or an extraction screw as shown in Figure 1.

An outlet 6 of the vaporized products (gases and oils) is installed between the inlet 4 and the outlet 5, advantageously fixed on the outer enclosure 2. A variant can be obtained by allowing this gas outlet through a borehole made in the center The sealing of this fixed connection can be ensured by the use of sealed flanges.

The outlet 6 is advantageously connected to a gas extraction means, for example a draft fan placed further on the gas circuit. The relative vacuum created by this draft fan ensures that any leakage into the enclosure and its connections does not result in an outward gas leakage, but an outward air leakage to the interior. This is a safety measure because it is safer to return air into the enclosure than to vent gas to the atmosphere. But this air brings oxygen which disturbs the thermolysis. It is therefore essential to take care of the tightness of the connections of the installation.

According to a variant of the invention, the chamber 2 may be rotatable and the inner axis 3 fixed relative to the ground, thus allowing a relative rotational movement. In this variant, the connections of the enclosure with the inputs and outputs of the products are obviously more complex to achieve.

According to another variant of the invention, the relative movement may be an alternating translation which ensures the relative movement between the chamber 2 and the inner axis 3.

According to another variant of the invention, several rotating internal axes may be arranged in a parallel arrangement in the same enclosure, so that they rotate synchronously so as not to come into contact during their use.

Typically the internal mechanism is rotated by a geared motor 11 itself regulated in speed by a regulating means 10.

According to the invention, the chamber 2 is equipped with mechanical elements 20 and the inner axis 3 is equipped with mechanical elements 30. These elements are placed facing each other and are therefore movable relative to each other. other. In order not to damage the material, an air gap 8 is preferably provided, preferably with a minimum value of 2 mm.

These elements have a major mechanical role according to the invention, namely that they accelerate the thermolysis reaction by a fragmentation action of the raw material particles. Indeed, under the effect of the heat prevailing in the enclosure, the material has on the surface particles of raw material is transformed, emits vapors and becomes fragile. Thanks to the action of the mechanical elements, this brittle surface is crushed and unhooked. Then the underlayer of material is released and subjected in turn to the heat of the enclosure; it is then transformed by thermolysis. This mechanical action by fixed and mobile elements is essential to improve the thermolysis compared to the prior art.

As indicated in FIG. 2, the shape of the mechanical elements 26 and 36 is advantageously configured in order to create an air gap 8 which varies between a maximum value 81 and a minimum value 82. The raw material particle 9, present in the air gap when its value decreases from a maximum value, is subjected from the faces of the mechanical elements to mechanical forces of compression and shear tending to fragment. Then, as the air gap value increases, the particles are released from the air gap 8.

According to a variant of the invention as shown in FIG. 2, the fragmentation is obtained by the application of axial compression using mechanical elements having the shape of movable beveled fingers 36 and fixed counter-fingers. .

According to another variant of the invention as shown in FIG. 3, the fragmentation is obtained by the application of radial compression using mechanical elements having the shape of moving cams and fixed counter-cams. .

More generally, the best fragmentation is obtained by the application of fragmentation efforts in a predominantly axial direction, as shown in FIG. 4. For this purpose, it is advantageous: to consider, on the one hand, the vector normal average of the geometric surface of the face of the movable mechanical element 32 located vis-à-vis the particle 9 of raw material trapped in the gap 8, corresponding to the vector average of all normal vectors of the face considered, - to consider, on the other hand, the average normal vector of the geometrical surface of the face of the fixed mechanical element 22 also situated opposite the particle 9 of raw material trapped in the gap 8, corresponding to the mean vector of all the normal vectors of the face considered, and - to ensure that each of these average normal vectors forms an angle less than 45 ° with respect to the axial line 200 parallel to the axis of rotation of the inner axis 3.

Thus, the fragmentation efforts are essentially axial, in a direction inscribed between the axial line 200 and the line inclined at 45 ° 201.

In the same way, it is also advantageous to apply fragmentation efforts in a predominantly radial direction, as shown in FIG. 5. For this purpose it is advantageous: to consider, on the one hand, the average normal vector of the geometric surface of the face of the movable mechanical element 32 situated opposite the particle 9 of raw material trapped in the gap 8, corresponding to the vectorial mean of all the normal vectors of the face considered, - to consider, on the other hand, the average normal vector of the geometric surface of the face of the stationary mechanical element 22 also located opposite the particle 9 of raw material trapped in the air gap 8, corresponding to the vector average of all the normal vectors of the face considered, and - to ensure that each of these average normal vectors forms an angle less than 30 ° with respect to the radial line 100 resulting from the axis of rotation of the m Internal Mechanism 3.

Thus, the fragmentation efforts are essentially radial, in a direction inscribed between the radial line 100 and the line inclined at 45 ° 101.

According to a variant of the invention, the gap 8 between the mechanical elements 20 and 30 decreases between the inlet 4 and the outlet 5 so as to gradually tighten the available space when the material is reduced into smaller and smaller elements by the mechanical action of the mechanical elements. The invention gives good results regardless of the compactness of the enclosure, that is to say regardless of the ratio between volume and surface of the enclosure. However, it is advantageous to maximize the inner surface of the enclosure 2 in contact with the material for a given total volume. Because this surface participates in thermolysis by heating the raw material, as described below. Thus, it is recommended to have an enclosure 2 whose length is greater than twice the inside diameter measured from the inner surface 21.

According to a variant of 1'invention, it is advantageous to have several inputs 4 of raw material. A first placed at the end of the enclosure allows to introduce large elements that require a longer residence time; a second placed towards the center of the enclosure makes it possible to introduce smaller elements which will undergo a shorter residence time, before the exit 5.

According to a variant of 1'invention, it is advantageous to have a reagent inlet, such as for example a "fluxing" additive whose function is to make the ashes more liquid, which facilitates their evacuation through the outlet 5, the instead of having viscous ashes that do not behave like solid dust or liquid. This is particularly the risk if raw material containing corn cob containing potassium, a source of pasty ash beyond a temperature of 600 ° C, is used.

According to a variant of 1'invention, it is advantageous to leave the vaporized products (gases and oils) in several outlets 61 and 62 along the enclosure. Thus the water vapor created at the beginning of the thermolysis, thus in the first part of the enclosure, can be extracted separately from the gases created at the end of the thermolysis when the raw material is the hottest.

According to a variant of 1'invention, it is advantageous to control the extraction rate of the vaporized products, for example by means of a speed control of a gas draft fan located downstream of the gas outlet 6. Another solution is obtained by using a register valve regulated in opening according to the desired flow rate.

According to the invention, the raw material is converted by thermolysis under the effect of a high temperature. Since the raw material is initially at room temperature and the thermolysis reaction is endothermic, it is necessary to provide an energy supply in the device of the invention.

A first solution is to introduce air or oxygen into the chamber to obtain a partial combustion of the material present. This is not a recommended solution because combustion is an undesirable reaction, as explained above about the lack of oxygen sought.

According to an advantageous variant of the invention, the supply of energy is ensured by the implantation of a caloric supply means 7 on the envelope 21 of the enclosure 2, associated with an insulating material 72 which ensures that the caloric energy supplied is well transmitted in the enclosure and not outwardly.

The caloric intake means 7 may be designed to circulate a hot heat transfer fluid therein and conductionally transmit this heat into the enclosure. This heat transfer fluid may be a mineral oil, a molten salt or any other fluid whose temperature is higher than that desired in the enclosure. For example with a fluid heated to 600 ° C, it is possible to heat the enclosure to above 500 ° C.

According to another variant of the invention, a caloric intake means 7 may also be implanted in the inner axis 3.

According to another variant of the invention, the energy supply is ensured by the installation of a caloric supply means by means of a jousting effect based on electrical resistances, integrated in the outer wall 21 of enclosure 2 and / or in the inner axis 3.

According to a variant of the invention, 11 caloric energy supply is provided by different means of heat supply 7 placed distinctly along the device 1. Thus, it is possible to provide 11 caloric energy with a different power and temperature according to the invention. position in the enclosure. Each caloric intake means 7 is then managed independently of the others.

For example, it is possible to bring a great power at the beginning of the device 1 in order to heat the incoming material as quickly as possible, then the temperature is voluntarily stabilized on the long part of the reaction, then it is possible to raise the temperature by end of thermolysis, for example in order to liquefy the ashes by applying a temperature above their melting point. Conversely, it is possible to cool the ashes so as not to exceed or approach their melting point.

It is also possible to proceed step by step in order to select the reactions involved: firstly, a vaporisation of the residual water contained in the raw material is carried out, for example at 1000 ° C .; then a rise in temperature with stabilization at 200 ° C to roast and weaken the material; then a temperature rise with stabilization at 600 ° C to thermolyze the previously roasted material.

According to a variant of 1'invention, it is advantageous to install mechanical elements 20 or 30 which have good heat conduction properties, and the same for the means for fixing these elements on their support, that is to say the inner wall 21 or the outer surface of the shaft of the mechanism 31. Advantageously, the material employed must have a thermal conductivity greater than 50 W / mK.

According to the invention, the relative movement between the chamber 2 and the internal mechanism 3 makes it possible to drive the set of reagents in an axial displacement movement from the raw material feeds 4 to the outlets 5. This training is for example obtained by means of at least partial spiral-shaped elements 300 arranged regularly along the device 1. Thus, the rotation allows a homogeneous circulation of the products in the enclosure 2. A partial turn is a coil that unfolds at an angle of less than 360 °. The angle of the partial turn must however be more than 90 ° to ensure effective action of this portion of coil 300.

A variation of the invention ensures homogeneous movement of material by placing the equipment vertically or inclined with the raw material input in the up position. A natural flow, due to the gravity and the inclination of the device, is thus obtained but can also be reinforced by the presence of spiral elements 300.

The present invention also relates to a method of thermolysis using the devices and configurations described above.

Claims (18)

1 - Thermolysis device (1) comprising, on the one hand, an enclosure (2), comprising at least one inlet of raw material particles (4), at least one outlet of treated products (5) and at least one outlet of products gaseous (6), on the other hand a caloric supply means (7) arranged so as to regulate the temperature inside said enclosure (2), an inner axis (3) placed inside said enclosure (2), characterized in that said inner axis (3) and said enclosure (2) are rotatably mounted relative to each other and in that said enclosure (2) is divided into at least two portions communicating with each other via at least one gap (8) delimited by a first mechanical element (30), fixed on said inner shaft (3), and a second mechanical element (20) fixed on the inner face (21) of said enclosure (2), the local width of said gap varying between a maximum value (81) and a minimum value (82) depending on the relative position of the inner axis (3) relative to said enclosure (2). 2 - Device (1) according to the preceding claim, characterized in that said gap (8) has a minimum width of 2 mm. 3 - Device (1) according to one of the preceding claims, characterized in that said enclosure (2) is rotatably mounted about said inner axis (3). 4 - Device (1) according to one of claims 1 to 2, characterized in that said inner shaft (3) is rotatably mounted about its longitudinal axis. 5 - Device (1) according to one of the preceding claims, characterized in that a speed regulating means (10) makes it possible to adjust the mechanical torque of the relative movement between said enclosure (2) and said inner shaft (3). ). 6 - Device (1) according to one of the preceding claims, characterized in that the average vector normal to the faces (22) (32) defining the air gap (8) has a direction inscribed in an angle cone less than 30 ° with respect to the radial direction of the geometry of revolution of the inner axis (3). 7 - Device according to the preceding claim, characterized in that said first (20) and second mechanical elements (30) respectively have the shape of a cam (25) and a counter-cam (35). 8 - Device according to one of claims 1 to 5, characterized in that the average vector normal to the faces (23) (33) defining the air gap (8) has a direction inscribed in an angle cone less than 45 ° relative to the axial direction of the geometry of revolution of the inner shaft (3). 9 - Device according to the preceding claim, characterized in that said first (20) and second mechanical elements (30) respectively have the shape of a finger (26) and a counter-finger (36) having beveled faces delimiting said gap (8). 10 - Device according to one of the preceding claims, characterized in that said first (20) and / or second mechanical elements (30) consist of a material having a thermal conductivity greater than 50 W / mK. 11 - Device according to one of the preceding claims, characterized in that at least one of the first (20) and / or second mechanical elements (30) is equipped with a caloric intake means by electric joule effect or by fluid coolant. 12 - Device according to one of the preceding claims, characterized in that said device (1) comprises at least one axial transfer means (300) disposed within said enclosure (2). 13 - Device according to the preceding claim, characterized in that said axial transfer means (300) comprises one or more spiral portions. 14 - Device according to one of the preceding claims, characterized in that the axis passing through said input of raw material particles (4) and said output of treated products (5) is inclined at a maximum inclination of 45 ° relative to at the horizontal. 15 - Device according to one of the preceding claims, characterized in that it comprises a plurality of caloric intake means (7) each associated with a temperature control means (71) defining zones having independent temperature regimes to the interior of said enclosure (2). 16- Device according to the preceding claim, characterized in that it comprises at least one gas outlet (61,62) per zone of said enclosure (2). 17. A method of thermolysis of organic material implementing a device according to one of the preceding claims. 18- The method of thermolysis of organic material according to the preceding claim characterized in that said enclosure (2) is placed in a confined atmosphere.