CA2741266A1 - Device for drying solid biomass and use of said device - Google Patents

Abstract

The invention relates to a solid biomass drying device comprising a plurality of cyclones (1A to 1E) arranged in series, each cyclone comprising a conical lower part, of which a first cyclone (1A) comprises a hot gas supply pipe ( 2) and a gas outlet pipe (3A) and whose other cyclones (1B to 1E) comprise an inlet pipe (4B to 4E) and an outlet pipe (3B to 3E) of the gas, each cyclone having a lower vertical flow (5A to 5E) of flow of solids to the ceiling of the adjacent cyclone. According to the invention, said hot gas supply pipe (2) opens into the ceiling of the upper cyclone (1A) and said gas inlet pipe (4B to 4E) of the other cyclones also opens into the ceiling of the corresponding cyclone. .

Description

SOLID BIOMASS DRYING DEVICE AND
USE OF THIS DEVICE

The invention relates to a device for drying solid biomass and use of this device.
In the context of climate change and the imposition of emission quotas for carbon dioxide emitted by the installations industrial and especially energy-based production solid fossil fuels, it appears that capture and storage of carbon dioxide which is envisaged in the medium and long term for large facilities will be insufficient to meet the factor four of dividing carbon dioxide emissions into 2050.
The capture and storage of carbon dioxide will have to be complemented by the use of agricultural and forestry biomasses for medium and low capacity installations that are able to collect these biomasses in a limited geographical area.
These biomasses of natural origin have the disadvantage of high moisture content, which has a detrimental effect on performance of conversion plants for both combustion and gasification. Knowing that technological efforts must be brought on all stages of the thermochemical conversion of the biomass, it is necessary to improve the performance of the drying and to prevent drying from being emitted specific carbon dioxide.
It is known in industries that use biomass of the type manufacture of particle board, to carry out this oven drying rotating, powered by fumes produced by generators fueled by natural gas. These fumes help to reduce humidity

2 biomass starting point, which is 55 to 60%, at around 20 to 25%, at the price of expensive energy consumption and generating carbon dioxide.
The use of a rotary kiln is a primary technique of solid gas contact and little compact, known for performance average biomass drying. On the other hand, it has the advantage to tolerate coarse biomass and to be well adapted to papermaking chips but to be limited by fine sawdust contents.
There are also technologies in development for the drying of lignite with high moisture content which are carried out in bed dense fluidized fluid having submerged heat exchangers traversed by steam. But these technologies are adapted to low lignite particle size, for combustion in the finest pulverized state.
The patent document US 2005/0274067 discloses a device for drying of biomass as fuel in a plant cement plant. The cement raw material containing these biomasses is dried in a preheating section having a series of stages of cyclone preheating, the raw material being introduced into the cyclone higher and the hot gas from a rotary kiln being introduced in the lower cyclone, the drying taking place against the current of the solids and gases.
The upper cyclone preheater receives the solids by a lateral horizontal pipe also bringing the gas at the end of gas loop and the solids separated from the gases flow from a cyclone to the other by a vertical pipe inferior to the cyclones. The lower cyclone preheater receives the hot gas through a lateral horizontal pipe at the beginning of the gas loop.
Such a drying device poses the technical problems following.

3 Such a drying device is very bulky, each cyclone having a diameter of about 10 meters and the total height of the series of cyclones being of the order of 80 meters, and can not be installed at any place.
Counter current drying applies exclusively to a cement plant where the supply of hot gas is lower part.
The invention solves these technical problems and proposes a drying device specifically for biomass, which is compact and particularly integrated in a conversion plant thermochemical fast fluidized bed, while ensuring a strong mixing turbulence with hot gases.
To do this, the invention proposes a drying device for solid biomass comprising a plurality of cyclones arranged in series, of which a first cyclone comprises a gas supply line hot and a gas outlet pipe and whose other cyclones have an inlet pipe and a gas outlet pipe, each cyclone with a lower vertical line flow of solids to the ceiling of the adjacent cyclone, characterized in that said hot gas supply pipe leads into the ceiling of the upper cyclone and the said pipe other cyclones also leads to corresponding cyclone ceiling.
To improve thermochemical conversion efficiencies biomasses and reduce their humidity to about 10%, humidity equivalent to that of coal-type solid fossil fuels, it it is necessary to carry out a drying using a strong mixing turbulence with hot gases containing oxygen and possibly solids, without igniting these biomasses and ensure sufficient residence time for these moisture migrations

4 in porous biomass particles that have been prepared in granulometry. An improvement in performance requires reducing the granulometric spectrum of input biomass to control their residence time and make it homogeneous. The compactness of the device drying is essential to reduce investment costs.
The invention also relates to a use of such a device solid biomass drying, characterized in that said hot gas is taken from combustion fumes or synthesis gas from a temperature of about 600 to 700 C.
The invention finally relates to a use of such a device for solid biomass drying, characterized in that inert solids are mixed with the biomass fed and are recovered at the outlet of the drying device to be recycled into the biomass fed.
The invention is described below in more detail with the help of figures representing only a preferred embodiment of the invention.
FIG. 1 is a schematic view in elevation of a device biomass drying according to the invention.
FIG. 2 is a detailed perspective view of such a device biomass drying according to the invention.
FIG. 3 is a top view of detail of such a device for biomass drying according to the invention.
FIG. 4 is a schematic plan view of an installation of rapid fluidized bed thermochemical conversion equipped with a biomass drying according to the invention.
As illustrated in FIG. 1, a drying device of solid biomass according to the invention comprises a plurality of high-speed cyclones arranged in series, five cyclones 1A to 1E according to the example shown, each cyclone having a lower portion conical and a cylindrical upper part.

WO 2010/05240

5 PCT / FR2009 / 052048 A first cyclone 1A comprises a supply line hot gas 2 and a gas outlet pipe 3A and the other cyclones 1B to 1E comprise an inlet pipe 4B to 4E and a pipe of 3B to 3E output of the gas. Each cyclone has a vertical pipe 5A to 5E lower solids flow to the ceiling of the cyclone adjacent, arranged on the axis of symmetry of the corresponding cyclone.
The hot gas supply pipe 2 opens into the upper cyclone ceiling 1A and gas inlet line 4B to 4E
other cyclones also lead into the cyclone ceiling corresponding.
The supply line 2 and the inlet lines 4B to 4E of the gas are inclined, at least 200 from the horizontal, in a last section in the upper part of the corresponding cyclone and flow directed downwards The outlet pipe 3B to 3E of the gas is arranged laterally to the conical part of the corresponding tilting cyclone down.
The biomass is fed into the upper cyclone 1A by a vertical pipe 6 disposed on the axis of symmetry of this cyclone.
The plurality of cyclones 1A to 1E is arranged in a tower, their axes of symmetry being aligned in a line X. This arrangement minimizes the support structure.
The drying gas containing the evaporated moisture at the outlet of the last cyclone lE, evacuated by the exit pipe 3E, is directed towards filtration and condensation for reuse of water and then a transfer to a downstream processing process or rejection to the atmosphere after possible treatment of volatile substances contained.
Figures 2 and 3 show in more detail the output and gas inlet between two cyclones 1B and 1C. In these figures

6 are also represented the lower vertical pipes 5A and 5B flow of the corresponding solids.
The 4C gas inlet pipe opens into the ceiling of the cyclone 1C near the periphery of the latter preferably by a slot in an arc of a circle, of constant width. The peripheral edge external of this slot is arranged in continuity with the wall cylindrical cyclone 1C, so as not to reduce the speed of the solids.
Cyclone 1B has a flue outlet pipe lateral 3B, by its lower conical portion.
Output line 3B and inlet line 4C are connected in a single pipe with a length-to-length connection geometry minimum to connect the inclined lateral outlet pipe 3B of gas through cyclone 1B lower cone with gas inlet pipe 4C warm to the next cyclone ceiling 1C.
The inclined exit pipe section 3B is followed by a vertical run pipe section 7 and then the pipe section inclined inlet 4C. Preferably, an angle of 450 in a plane horizontal projection is laid out between the driving section of inclined lateral exit 3B of cyclone 1B and the driving section inclined inlet 4C at the ceiling of the adjacent cyclone 1C.
According to a preferred use of this drying device of solid biomass, the hot gas introduced into the feed pipe 2 is taken from gases from a combustion plant, by example air combustion, oxycombustion or thermochemical cycle, or on synthesis gas, at a temperature of about 600 to 700 C.
Advantageously, to improve the contacting of the gases with the biomass to be dried, inert solids role of coolant, for example sands, clays, ashes circulating or minerals, are mixed with the biomass fed by the pipe 6 and are recovered at the outlet of the drying device,

7 separated by partial sieving of the dried biomass, for recycling in the biomass to be dried fed at the head of the drying device, as illustrated by a dotted line 16 in FIG.
This loop of inert solids mixed with biomass to dry with the hot gases favors the flows by rinsing the sheaths, between successive cyclones and increases contact with biomass to accelerate the kinetics of drying.
FIG. 4 illustrates an example of use of this device of drying of solid biomass.
This solid biomass drying device, comprising example two cyclones IA and 1B in series, is installed in a loop to fast fluidized bed comprising a reactor 10, a separation cyclone 11 associated and a return pipe 12 solids from this cyclone towards the reactor, the supply pipe 2 in hot gas being fed by gases withdrawn at the outlet of the separation cyclone 11.
The dried biomass is fed via the pipe 6 and at the outlet the drying device, evacuated via line 5B, is injected into the bottom of the reactor 10. The drying gas containing evaporated moisture at the outlet of the last cyclone 1B, is evacuated via line 15.
Solids are withdrawn from the return pipe 12 and after cooling by an exchanger 13 at a temperature of about 600 C to 700 C, are mixed by means of a pipe 14 to the biomass supplied to the drying device, via the pipe 6.

Claims (11)

1. A solid biomass drying device comprising a plurality of cyclones (1A to 1E) arranged in series, each cyclone having a conical lower portion, including a first cyclone (1A) comprises a hot gas supply pipe (2) and a gas outlet pipe (3A) and whose other cyclones (1B
1E) have an inlet pipe (4B to 4E) and a pipe (3B to 3E) of the gas, each cyclone having a lower vertical pipe (SA to 5E) of solid flow towards the ceiling of the adjacent cyclone, characterized in that hot gas supply pipe (2) opens into the upper cyclone ceiling (1A) and the said inlet pipe of the other cyclones (4B to 4E) also leads to corresponding cyclone ceiling. 2. Device according to the preceding claim, characterized in that said supply line (2) and said inlet lines (4B to 4E) of the gas are inclined in a last portion partially high of the corresponding cyclone and directed flow towards the low. 3. Device according to the preceding claim, characterized in that said inclination is at least 20 relative to the horizontal. 4. Device according to one of the preceding claims, characterized in that said gas outlet pipe (3B to 3E) is arranged laterally to said conical portion of the cyclone and inclined towards the low. 5. Device according to one of the preceding claims, characterized in that the biomass is fed into said upper cyclone (1A) by a vertical pipe (6) disposed on the axis of symmetry of this cyclone. 6. Device according to one of the preceding claims, characterized in that said plurality of cyclones (1A to 1E) is arranged in a tower, their axes of symmetry (X) being aligned. 7. Use of a solid biomass drying device according to one of the preceding claims, characterized in that said hot gas is taken from gases from an installation of combustion or on synthesis gas, at a about 600 to 700 ° C. 8. Use of a solid biomass drying device according to one of claims 1 to 6, characterized in that solids inert are mixed with the biomass fed and are recovered at the outlet of the drying device to be recycled in the biomass fed. 9. Use of a solid biomass drying device according to the Claim 7 or 8, characterized in that it is installed in a fast fluidized bed loop comprising a reactor (10), a associated separation cyclone (11) and a return line of solids (12) from this cyclone to the reactor, said pipe supplying hot gas (2) being fed with gases withdrawn at the outlet of said separation cyclone (11). 10. Use according to the preceding claim, characterized in that that the dried biomass at the outlet of the drying device is injected into said reactor (10). 11. Use according to claim 9 or 10, characterized in that solids are withdrawn from said return line (12) and are mixed with the biomass fed to the drying device.