FR3060603A1 - DEVICE AND PROCESS FOR THE PRODUCTION OF DIFFERENTIATED PRODUCTS, IN MODULAR PROPORTIONS, FROM A PYROLYSIS OF PLANT BIOMASS. - Google Patents

Abstract

The object of the invention is a device for producing differentiated by-products by pyrolysis of biomass comprising biomass storage means (10), with a feed hopper (10-2) in the lower part, an oven ( 12) inclined, controlled supply means (14) of said furnace and a burner (18) emitting combustion gases, characterized in that it comprises an exchanger (20), integral with the pyrolysis furnace (12), comprising : - a first inlet (20-1) of the combustion gas from the burner (18), at a temperature T1, directly coming from the burner, with a first direction of circulation of the first flow, - a first outlet (20-2) of the first flow of combustion gases from the burner (18) at a temperature T2, with T2 <T1 - a second inlet (20-3) positioned to the right of said first outlet (20-2), receiving the pyrolysis gases from the 'upstream of the pyrolysis furnace (12) at a temperature T3, - a second outlet (20-4) arranged in line with the first inlet (20-1), with a sen s circulation of a second flow opposite to that of the first flow, at a temperature T4 with T4> T3, - the second flow from the second outlet (20-4) being connected downstream of the pyrolysis furnace (12 ). The invention also covers the device obtained.

Description

(57) The object of the invention is a device for producing differentiated by-products by pyrolysis of biomass comprising biomass storage means (10), with a feed hopper (10-2) in the lower part, an inclined furnace (12), controlled supply means (14) of said furnace and a burner (18) emitting combustion gases, characterized in that it comprises an exchanger (20), integral with the pyrolysis furnace (12) ), comprising:

- a first inlet (20-1) of the combustion gas from the burner (18), at a temperature T1, directly coming from the burner, with a first direction of circulation of the first flow,

- a first outlet (20-2) of the first flow of combustion gases from the burner (18) at a temperature T2, with T2 <T1

- a second inlet (20-3) positioned in line with said first outlet (20-2), receiving the pyrolysis gases from the upstream side of the pyrolysis furnace (12) at a temperature T3,

- a second outlet (20-4) arranged in line with the first inlet (20-1), with a direction of circulation of a second flow opposite to that of the first flow, at a temperature T4 with T4> T3,

- the second flow from the second output (20-4) being re-

linked to the downstream side of the pyrolysis furnace (12).

The invention also covers the device obtained.

DEVICE AND PROCESS FOR THE PRODUCTION OF DIFFERENTIATED PRODUCTS, IN MODULAR PROPORTIONS, FROM A PYROLYSIS OF PLANT BIOMASS

The present invention covers a device and a method for producing differentiated products, in adjustable proportions, from a pyrolysis of plant biomass. In order to limit green waste or more generally plant biomass, and even to enhance it rather than simply burning it to collect the calories emitted, there are known devices having this objective.

Thus we know the patent US 9434895 for the production of biochar, a finely ground charcoal.

The carbonaceous waste is introduced into a reactor, without oxygen, by pyrolysis, the products resulting from the thermo-transformation of the carbonaceous material in the form of gaseous and liquid fuel are burned to produce heat which is recovered, the biochar also produced is collected .

Patent WO 2014155058 also describes the production of biochar by pyrolysis of wood, this patent providing for sending hot gases resulting from the combustion of a fuel in a cell independent of the pyrolysis furnace to reduce the moisture content of the wood in a first step then heat the wood with hot gases resulting from the combustion of fuel to ensure the pyrolysis of said wood secondly, take part of the gases resulting from the pyrolysis to burn them in the cell, divert part of the inert gas from combustion to regulate the flow of heat and air to control the pyrolysis reaction in the pyrolysis furnace.

The only valued product is biochar, the aim being to limit the diffusion of undesirable gases such as methane during pyrolysis.

Another document WO 2007033642 describes a biomass reactor intended to be pyrolyzed, comprising an enclosure with a double wall so as to introduce a heat exchanger in this double wall for circulation of the pyrolysis gases in order to preheat the combustion air.

We also know that when the biomass is heated at high temperature and very quickly, we obtain essentially combustible gas and liquid fuel, if we heat at moderate temperature, we obtain more vegetable charcoal.

Taking into account this knowledge of the prior art, the method and device of the present invention aim to obtain by-products of the pyrolysis of biomass continuously and with a dosage of the quantities of products obtained as a function of requirements.

The method and device are now described in detail according to a particular, non-limiting embodiment, with reference to the single appended figure, in which the drawing represents a diagram of the device according to the present invention.

FIG. 1 shows biomass storage means 10, a pyrolysis furnace 12, controlled supply means 14 of the furnace with biomass, means 16 for recovering the by-products, a burner 18 and an exchanger. 20.

The biomass storage means 10 comprise a biomass tank 10-1 with a feed hopper 10-2 in the lower part, connected in a sealed manner to the pyrolysis furnace 12, through a transfer lock, this lock comprising means sealed in order to prevent the passage of pyrolysis gases into the biomass tank, the biomass tank 10-1 also comprising an opening 10-3 with closure means in the upper part, intended to regularly allow the supply of the biomass to be treated and a tap 10-4 with an extractor 10-5 making it possible to evacuate the combustion gases from the burner 18 as will be explained further on. A 10-6 connection provided to the right of the hopper is provided to introduce said combustion gases.

The direction of movement of the biomass in the reservoir 10-1 is vertical and with a gravity effect. Any means to allow forced movement in the hopper is put in place to avoid any blockage. Such means can be in the form of vibrators and / or pushers.

The pyrolysis furnace 12 is of the horizontal, static type with an inlet 12-1 and an outlet 122.

Entrance 12-1 is located to the right of feed hopper 10-2. Upstream of this inlet, controlled supply means 14 are provided in the form of a piston 14-1 with reciprocating movements, intended to push over a small distance so as to advance the biomass in said furnace, along an axis. horizontal or slightly inclined.

The piston 14-1 is perforated so as to allow the gases to pass.

An outlet nozzle 12-3 is positioned at the upstream end of the pyrolysis furnace 12.

The pyrolysis furnace 12 comprises another inlet nozzle 12-4 for the supply of hot gas as explained above.

The pyrolysis oven 12 further comprises an evacuation 12-5 by gravity of the vegetable charcoal produced, to a storage 12-6. This discharge is located at the downstream end of said pyrolysis furnace 12. This discharge takes, in the embodiment presented, a shoe with adjustable inclination so as to maintain the filling of the furnace despite the loss of volume of the biomass during storage. pyrolysis.

A burner 18 is associated with the pyrolysis furnace 12. Such a burner 18 is supplied with fossil fuel, in a known manner, in order to allow the production of hot gases at a temperature between 300 ° C. and 1200 ° C. in order to initiate the pyrolysis. An injection of oxidizing gas by an injector 18-1, in this case air, is provided to supply said burner. This oxidizer gas can be optimized with a supply of pure oxygen so as to improve the performance and facilitate the recovery of the carbon dioxide at the outlet. The oxidant gas entering through the injector (18-1) can also be replaced by a hot gas, not necessarily reactive and coming from an external source of calories, in order to provide the system with part or all of the gas. energy required for pyrolysis. In particular, an industrial waste heat source or a natural heat source can be used in this way.

This burner 18 comprises an outlet 18-2 connected to the exchanger 20.

This burner also comprises an inlet for the pyrolysis gases 18-3, that is to say the fuel gas originating from the pyrolytic combustion, as will be better understood later in the description.

The exchanger 20 is integral with the pyrolysis furnace 12 and comprises a double flow.

It comprises a first inlet 20-1 of the combustion gas from the burner 18, at a temperature T1, directly coming from the burner, with a first direction of circulation of the first flow according to the arrow Fl in the exchanger 20, from downstream to upstream if we take the displacement of the biomass in the pyrolysis furnace 12.

The exchanger 20 has a first outlet 20-2 of the first flow of combustion gases at a temperature T2, which flow is directed by a line L0 towards the tap 10-6 to the right of the hopper in which the first flow of gas from combustion of the burner 18 enters to circulate in the raw biomass.

The double-flow heat exchanger has a second 20-3 inlet positioned to the right of the 20-2 outlet and a second 20-4 outlet positioned to the right of the 20-1 inlet, with a flow direction of a second flow following arrow F2, opposite to that of the first flow.

This second stream is composed of pyrolysis gas, issuing from the outlet 12-2 of the furnace 12, positioned at the upstream end of the pyrolysis furnace 12.

A circulator 20-5 upstream of the second inlet 20-3 ensures the forced circulation of the pyrolysis gas flow on a line L1 connecting the outlet nozzle 12-3 of the pyrolysis furnace 12 and the second inlet 20-3 of the 'exchanger 20.

The second stream, composed of pyrolysis gas at the outlet of the circulator 20-5, is at a temperature T3 at the inlet 20-3 and at a temperature T4 at the outlet 20-4 of the exchanger 20.

The outlet 20-4 of the exchanger 20 is connected downstream of the pyrolysis furnace 12, by a line L2 to the branch 12-4, so as to inject said pyrolysis gas and to circulate said pyrolysis gas, after the outlet 20-4 of the exchanger 20, against the current, in the biomass within the pyrolysis furnace 12, according to the fixed bed technique.

A valve 20-7 ensures the regulation of the second flow on the first outlet line L1 of the circulator 20-5, connected to the second inlet 20-3 of the exchanger 20.

Another line L3 provides the connection at the outlet of the circulator 20-5 with the inlet tapping 183 of the pyrolysis gas provided on the burner 18.

This line L3 is also equipped with a valve 20-8 which regulates the supply to the burner 18.

A line L4 provides the connection at the outlet of the circulator 20-5 with the means 16 for recovering the by-products. This line L4 is equipped with a valve 20-9 which regulates the supply of these means 16 for recovering the by-products.

These by-product recovery means 16 comprise a cyclone 16-1 intended to collect the dust in the form of fines, a condenser 16-2 intended to separate the liquid hydrocarbons and a storage 16-3 for the pyrolysis gas or syngas, called also syngas.

The entire device is preferably insulated in order to prevent cold spots and tar deposits, in particular at the level of the moving parts, the gas pipes and the exchanger.

The method according to the present invention consists in modulating the operation to adapt it to the needs.

The furnace 12 is loaded with biomass by the hopper 10-2 for priming. The piston is maneuvered to create this first charge.

The burner is supplied with fossil fuel, fuel oil or gas or even syngas previously stored, to supply hot combustion gas at temperature T1, which circulates in the exchanger 20 and heats the enclosure of the furnace 12 as well as its contents. The initial priming phase is not considered because it remains heterogeneous and only the phase under normal conditions is considered.

This combustion gas, after passing through the exchanger 20, following the arrow Fl, exits at 20-2 at a temperature T2 <Tl.

Line L0 leads said combustion gas to the nozzle 10-6 in order to pass through the raw biomass contained in the hopper 10-2, the temperature of the combustion gas further decreases and ensures drying and preheating of said biomass then this gas is extracted by the extractor 10-5.

The temperature in the enclosure is between 300 ° C and 1000 ° C, and as there is no air admission, the transformation of the carbonaceous material produces a pyrolysis gas comprising fractions condensable at room temperature. , purely gaseous fractions and dust linked to the degradation of the solid matter and to internal displacements in the enclosure.

The piston provides a force-feeding of the furnace 12 with biomass as a function of the needs and performs back and forth movements at a frequency f.

The pyrolysis gas is recovered upstream due to the gas circulation in the furnace from downstream to upstream since the extractor 20-5 ensures this circulation. The extractor has a variable flow rate so as to control the flow of coolant gas. The pyrolysis gas passes through the piston 14-1 of the controlled supply means 14 and leaves through the nozzle 12-3.

The pyrolysis gas is then distributed through three lines L1, L3 and L4 according to the degrees of opening of the valves 20-7, 20-8, 20-9.

Line Ll leads pyrolysis gas into exchanger 20, countercurrent to combustion gas from burner 18 so that the pyrolysis gas is used as a heat carrier and again enters oven 12 and brings calories directly. biomass in the oven enclosure and in particular finalizes the transformation of the carbonaceous material which is transformed into vegetable charcoal.

The pyrolysis gas, circulating along F2 and exiting at temperature T4> T3, is conducted via line L2 to the branch 12-4 in the chamber of the furnace 12.

The vegetable charcoal is collected at outlet 12-5 in a storage 12-6.

The pyrolysis gas can also be conducted via line L3 directly into the burner 18 so as to supply the quantity of fuel necessary to obtain the desired quantity and temperature T1 of the combustion gases at the burner outlet. The combustion is also managed by the supply of oxidizing gas through the injector 18-1, in this case air which provides the necessary oxygen or possibly a supply of pure oxygen as indicated further upstream in the description.

Another part of the pyrolysis gas can be conducted via line L4 to the means for recovering valuable by-products:

Dust liable to be burnt, to be used as carbon black, as filler,

Condensation of liquid hydrocarbons that can be used as bio-fuel or as a basis for green chemistry,

Clean syngas ready to be used or stored.

Thus, according to the needs, it is possible, with the same device:

to produce more vegetable charcoal and less by-products, hydrocarbons and syngas, by controlling the pyrolysis temperature and carrying out a slow pyrolysis between 300 and 500 ° C in the fixed bed. The biomass grinding dimension is between millimeters and centimeters. If the grinding dimension is small, biochar is obtained directly, that is to say carbon powder with industrial, agricultural or domestic activities. If the dimension is larger, the resulting vegetable charcoal is used as a household fuel and known as charcoal. In all cases, the continuous process according to the present invention has a better yield than the devices working in batches, discontinuously.

to produce less vegetable charcoal and more by-products, hydrocarbons and syngas, by controlling the pyrolysis temperature and carrying out a faster pyrolysis in the fixed bed up to a so-called flash pyrolysis. The temperature is higher, between 600 and 1200 ° C, the mass flow of gases is higher and the heat exchange coefficient between the heat transfer gas and the biomass is increased. Millimeter or submillimeter crushed biomass promotes rapid pyrolysis.

Thus, at a regulated temperature of the order of 500 ° C. and a dimension of centimetric biomass, a slow pyrolysis is carried out and the following mass fractions are obtained in a crude manner:

30% water

20% vegetable charcoal 3% liquid hydrocarbon 47% Syngas

These proportions are given when no consumption of pyrolysis gas in the burner is considered, so that the maintenance of the pyrolysis reaction in the oven is obtained either from the burner but supplied by other means, or by direct admission by the injector (18-1) of hot gases from an external source.

The burner 18 can be supplied by line L3, with a fraction of syngas produced, the excess being stored.

The load is also controlled by the supply means controlled in an easy manner by the presence of the piston which ensures perfect regularity of the supply and a volume therefore an adjustable weight by the speed of movement of the piston and the frequency f.

The transfer of calories by the pyrolysis gas itself, which acts as a heat transfer fluid, makes it possible to reduce the loss of calories.

The circuit is shorter and also avoids wastage.

The system operates continuously after the initiation phase so that it is an asset for the production of vegetable charcoal by improving yield, reducing emissions to the atmosphere and enhancing certain by-products.

Finally, the choice of the ratios of the by-products confers an interesting flexibility of production, according to the needs, knowing that the tank and its hopper with its lock make it possible to introduce millimeter or centimeter biomass indifferently according to the needs.

The hopper with its lock has been described with a gravity circulation of the biomass but the hopper could be horizontal or inclined with any suitable pushing means such as a worm, a piston or a conveyor. In this arrangement, the airlock of the hopper is upstream of the furnace and can be directly the drying / preheating chamber, the pyrolysis gases then being able to pass through the biomass of the airlock before resuming the circuit according to the present invention.

Claims (13)

1. Device for the production of differentiated by-products, in adjustable proportions of vegetable charcoal of variable particle size - biochar and / or charcoal, syngas and hydrocarbon, by pyrolysis of biomass comprising means for storing biomass (10 ), with a feed hopper (10-2) in the lower part with an airlock, an oven (12), means (14) for controlled supply of said furnace with heat transfer fluid and a burner (18) emitting gas from combustion, so as to generate a fixed bed pyrolysis, characterized in that it comprises an exchanger (20), integral with the pyrolysis furnace (12), comprising: a first inlet (20-1) of the combustion gas from the burner (18), at a temperature T1, directly coming from the burner, with a first direction of circulation of the first flow, a first outlet (20-2) of the first flow of combustion gas from the burner (18) at a temperature T2, with T2 <T1, a second inlet (20-3) positioned to the right of said first outlet (20-2), receiving the pyrolysis gases from upstream of the pyrolysis furnace (12) at a temperature T3, a second outlet (20-4) arranged in line with the first inlet (20-1), with a direction of circulation of a second flow opposite to that of the first flow, at a temperature T4 with T4> T3, the second flow coming from the second outlet (20-4) being connected downstream of the pyrolysis furnace (12). 2. Device for the production of differentiated by-products by pyrolysis of biomass, in adjustable proportions of vegetable charcoal of variable particle size, of syngas and of hydrocarbon, according to claim 1, characterized in that it comprises a circulator (20- 5) upstream of the second inlet (20-3) which ensures the forced circulation of at least part of the pyrolysis gas flow via a line LI connecting the outlet connection (12-3) of the pyrolysis furnace (12) ) and the second inlet (20-3) of the exchanger (20), said line LI being equipped with a valve (20-7). 3. Device for the production of differentiated by-products by pyrolysis of vegetable charcoal biomass of variable particle size, of syngas and of hydrocarbon, in adjustable proportions, according to claim 1 or 2, characterized in that the biomass storage means (10) include a biomass tank (10-1) with a feed hopper (10-2), sealingly connected directly to the pyrolysis furnace (12), the biomass tank (10-1) comprising a tapping (10-4) with an extractor (10-5) making it possible to evacuate the combustion gases from the burner (18), a nozzle (10-6) provided to the right of the feed hopper (10-2) being provided to introduce said combustion gases from the burner (18). 4 Device for the production of differentiated by-products by pyrolysis of vegetable charcoal biomass of variable particle size, of syngas and of hydrocarbon in adjustable proportions, according to one of claims 2 or 3, characterized in that it comprises a line L3 ensuring the connection at the outlet of the circulator (20-5) with an inlet tapping (18-3) of the pyrolysis gas provided on the burner (18). 5 Device for the production of differentiated by-products by pyrolysis of vegetable charcoal biomass of variable particle size, of syngas and of hydrocarbon in adjustable proportions, according to claim 4, characterized in that the line L3 is also equipped with a valve (20-8). 6 Device for the production of differentiated by-products by pyrolysis of biomass, in adjustable proportions, according to one of claims 2 to 5, characterized in that it comprises a line L4 ensuring the connection at the outlet of the circulator (20-5 ) with the recovery means 16 of the by-products. 7 Device for the production of by-products differentiated by pyrolysis of biomass, in adjustable proportions of vegetable charcoal of variable particle size, of syngas and of hydrocarbon, according to claim 6, characterized in that it comprises a valve (20-9 ). 8 Device for the production of differentiated by-products by pyrolysis of biomass, in adjustable proportions of vegetable charcoal of variable particle size, of syngas and of hydrocarbon, according to claim 6 or 7, characterized in that the recovery means (16) of by-products include a cyclone (16-1) intended to collect dust in the form of fines, a condenser (16-2) intended to condense the liquid hydrocarbons and a storage (16-3) for pyrolysis gas or syngas, also says syngas. 9 Process for the production of differentiated by-products by pyrolysis of biomass, in adjustable proportions of vegetable charcoal of variable particle size, of syngas and of hydrocarbon, using an oven (12) according to one of the preceding claims, characterized in that that it consists in using a fixed bed through which at least part of the pyrolysis gases is passed as fluid, e heat transfer agent and in that this at least part of the pyrolysis gases is heated in a controlled manner by a auxiliary caloric source. 10 Process for the production of differentiated by-products by pyrolysis of biomass, in adjustable proportions, according to the preceding claim, characterized in that the at least part of the pyrolysis gases is heated by means of a burner using at least part of the syngas produced during pyrolysis. 11 A method of producing by-products differentiated by pyrolysis of biomass, in adjustable proportions, according to claim 9 or 10, characterized in that one 10 introduces centimetric biomass particles, the temperature of the pyrolysis gases is of the order of 300 to 500 ° C and the circulation speed is low so as to produce preferentially vegetable charcoal and less hydrocarbons and syngas . 12 A method of producing by-products differentiated by pyrolysis of biomass, in adjustable proportions, according to claim 9 or 10, characterized in that one 15 introduces millimeter-sized biomass particles, the temperature of the pyrolysis gases is between 600 and 1200 ° C and the circulation speed is fast so as to preferentially produce hydrocarbons and syngas and less vegetable charcoal. 13 A process for the production of differentiated by-products by pyrolysis of biomass, in adjustable proportions, according to claim 9 or 10, characterized in that one 20 introduces millimeter-sized biomass particles, the temperature of the pyrolysis gases is of the order of 300 to 500 ° C. and the circulation speed is low so as to produce preferentially biochar and less hydrocarbons and syngas. 1/1