CA2777339A1

CA2777339A1 - Process and apparatus for producing biocarbon

Info

Publication number: CA2777339A1
Application number: CA2777339A
Authority: CA
Inventors: Kai Sipilae; Yrjoe Solantausta; Carl Wilen
Original assignee: Valtion Teknillinen Tutkimuskeskus
Current assignee: Valtion Teknillinen Tutkimuskeskus
Priority date: 2009-10-13
Filing date: 2010-10-13
Publication date: 2011-04-21
Also published as: WO2011045473A1; EP2488604A4; EP2488604A1; FI20096059A0

Abstract

The invention relates to a process and apparatus for producing a biocarbon product from bio-based raw stock. According to the invention the bio-based raw stock is sorted by removing in the raw stock the fraction (19) that is undesired in terms of the production of biocarbon from the desired fraction (18) of the raw stock which is used for the production of biocarbon, the desired fraction (18) of the raw stock is fed to a fluidized-bed reactor (1), the undesired fraction (19) of the raw stock is fed to a combustion boiler (2) disposed in connection with the fluidized-bed reactor in order to produce energy fractions, a heat transfer material (6) to be used in the fluidized-bed reactor is warmed up in the combustion boiler (2) and the warmedup heat transfer material (6) is led to the fluidized- bed reactor (1), the bio-based raw stock (18) is heated in the fluidized-bed reactor in oxygen-free conditions to a temperature of 220 to 350 °C in the presence of the heat transfer material (6) in order to form a solid biocarbon product (9,10), and the heat transfer material (7) is circulated from the fluidized-bed reactor (1) to the combustion boiler (2) in order to warm up the heat transfer material.

Description

PROCESS AND APPARATUS FOR PRODUCING BIOCARBON

FIELD OF THE INVENTION

The invention relates to the process defined in the preamble of claim 1 and to the apparatus de-fined in the preamble of claim 13 for producing a bio-carbon product.

BACKGROUND OF THE INVENTION

Known from the prior art are different proc-esses and apparatuses for producing energy products from different kinds of raw stock by combustion tech-nology. It is known to use wood in order to produce energy.
In addition, known form the prior art is the production of biocarbon, e.g. charcoal, by charring.
Wood-based charcoal has become the focus of great in-terest in Europe, China and the USA, as CO2 emissions of coal-fired power stations and coke plants are tried to be reduced. Conventionally, shaft, rotary or multi-layer kilns are used in order to produce charcoal.
Typically, woodchips are fed to the apparatus e.g. in a chip size of 2 to 8 cm, dried to the moisture of 10 to 25 %, and charred at a temperature of 200 to 320 C
for approximately 20 to 30 minutes.
A problem in using wood in the production of energy is that it cannot be fed to large power station boilers in large proportions without significant changes in the devices, e.g. in the carbon boiler and feeder lines. In burning wood and charcoal, the prob-lem in power boilers that produce electricity is often the high ash content of wood fuels and thereby the contamination of the boiler and the increase of the corrosion risk, as well as the after-treatment of ash.

A functional fluidized-bed charring process and apparatus that are applicable for the production of biocarbon have not been developed before. For exam-ple, the fact that it is difficult e.g. to separate a product formed from wood and the fluidized-bed mate-rial has been conceived as a problem. Another problem has been the light structure of the product which has disturbed stable operation of a fluidized-bed reactor.
Known from publications US 2003/0221363, US
2009/0151251 and EP 2017325 is the production of a biocarbon-type product from biomass. The processes of the publications seem to be based mainly on prelimi-nary treatment of the raw stock for the production of a synthesis gas or a pyrolysis liquid.

OBJECTIVE OF THE INVENTION

An objective of the invention is to disclose a new type of a process and apparatus for producing a biocarbon product.

SUNIl4ARY OF THE INVENTION

The process and apparatus according to the invention for producing a biocarbon product are char-acterized by what is presented in the claims.
The invention is based on a process for pro-ducing a biocarbon product from bio-based raw stock.
According to the invention the bio-based raw stock is sorted by removing in the raw stock the undesired fraction in terms of the production of biocarbon from the desired fraction of the raw stock which is used for the production of biocarbon, the desired fraction of the raw stock is fed to a fluidized-bed reactor in order to produce biocarbon, the undesired fraction of the raw stock is fed to a combustion boiler disposed in connection with the fluidized-bed reactor. in order to produce energy fractions, a heat transfer material, preferably solid heat transfer particles, to be used in the fluidized-bed reactor is warmed up, e.g.
heated, in the combustion boiler, and the warmed-up, such as heated, heat transfer material is led to the fluidized-bed reactor, the bio-based raw stock is heated in the fluidized-bed reactor in oxygen-free conditions to a temperature of 220 to 350 C in the presence of the heat transfer material in order to form a solid biocarbon product, and the heat transfer material is circulated from the fluidized-bed reactor to the combustion boiler in order to warm up, such as heat, and purify the heat transfer material.
In addition, the invention is based on an ap-paratus corresponding to the process for producing a biocarbon product from bio-based raw stock. According to the invention the apparatus includes a fluidized-bed reactor in order to produce a biocarbon product and a combustion boiler in order to produce energy fractions and warm up a heat transfer material, these two being integrated together, and sorting means for the bio-based raw stock in order to sort the bio-based raw stock into a desired and undesired (19) fraction in terms of the production of biocarbon, feeding means in order to feed the desired fraction of the raw stock to the fluidized-bed reactor, and feeding means in order to feed the undesired fraction of the raw stock to the combustion boiler, means for leading the warmed-up heat transfer material from the combustion boiler to the fluidized-bed reactor, means for separating the heat transfer material from the biocarbon product that has been formed, and means for circulating the heat trans-fer material back to the combustion boiler in order to warm up and purify the heat transfer material.
A biocarbon product in this context means a product to be utilized as biocarbon. The biocarbon product may be in this context any biocarbon product, biocarbon, biocarbon fraction, biocarbon product frac-tion or equivalent. The biocarbon may be formed from suitable raw stock, and binders and/or additives may or may not be added to it.
The process according to the invention oper-ates in the temperature range of 220 to 350 C as an atmospheric pressure process and in oxygen-free state.
At higher temperatures, biocarbon grades that only in-clude a small amount of volatile matter may be pro-duced, e.g. for coke plants. The biocarbon product be-ing formed is always substantially in a solid state.
Preferably, the bio-based raw stock is cured in order to form the biocarbon product. In one embodiment the bio-based raw stock may be dried before curing to the moisture of approximately 10 to 15 The drying may be performed by utilizing waste heat of the apparatus or the plant.
Preferably the fluidized-bed reactor to be used for the production of biocarbon is combined with the combustion boiler which is used to produce energy and preferably to warm up and/or purify the heat transfer material, to treat the possible residual fractions developed in the production of biocarbon and/or to produce energy from lower-grade starting ma-terial. The combustion boiler may be a separate com-bustion boiler for the production of energy or a com-bustion boiler of the power station or equivalent. In one embodiment the fluidized-bed reactor designated for the production of biocarbon is a supplementary ap-paratus in the boiler of the power station. In addi-tion, the annual variations of the combustion boiler, e.g. a traditional CHP power station, may be utilized by the integrated fluidized-bed reactor and combustion boiler connection, so that during summer time when low energy demand, such as low steam load, prevails, a large biocarbon production capacity is provided.

The energy fractions to be formed in the com-bustion boiler may include heat, electricity, steam, combustion gases or the equivalent. The heat may be bound e.g. to the heat transfer material and conducted by the heat transfer material to a desired destina-tion.
In a preferred embodiment heat is brought to the production of a biocarbon product by the solid heat transfer material. In addition, heat may be brought to the production of the biocarbon product by fluidizing the fluidized bed with hot oxygen-free or low-oxygen circulating gases or combustion gases of the boiler. Also, the use of superheated steam is pos-sible as a heat-bearing material.
The solid heat transfer material, preferably in the form of particles, may be heated to a desired temperature of 300 to 1000 in the combustion boiler and/or outside the boiler, e.g. by guiding the heat transfer material through a separate heat exchanger and warming it up by hot combustion gases. The combus-tion gases may come from the combustion boiler or any suitable thermal reactor.
In one embodiment of the invention the heat transfer material is led into contact with the bio-based raw stock in the fluidized-bed reactor in order to provide direct transfer of heat. In one embodiment the heat transfer material acts at the same time as the fluidized-bed material of the fluidized-bed reac-tor either alone or with another bed material.
In one embodiment of the invention the heat transfer material is led to a heat exchanger provided inside the fluidized-bed reactor. In this case, suit-able bed material is used in the fluidized-bed reactor as the fluidized-bed material, or the fluidized bed is formed only by the bio-based raw stock. In one, alter-native embodiment the heat transfer material is led to a separate heat transfer material bed or heat transfer bed, e.g. a woodchip bed or equivalent, of the fluid-ized-bed reactor.
The transfer of heat from the heat transfer material to the bio-based raw stock may take place di-rectly by the heat transfer material or indirectly through a heat exchanger or other separate heat trans-ferring means accommodated within the fluidized bed.
In one embodiment a heat transfer material selected from the group of sand, magnetite, ash blend and their combinations is used.
In using hot sand or equivalent solid heat transfer material in the production of biocarbon, a higher heat transfer, typically approximately 100 to 180 W/m2K, than that of the conventional reactor de-vices designated for the production of charcoal, is substantially achieved.
In one embodiment of the invention the heat transfer material is separated from the biocarbon product that has been formed, and it is circulated to the combustion boiler.
In a preferred embodiment the biocarbon prod-uct that has been formed is substantially lighter than the fluidized-bed material and/or the heat transfer material, and it is separated in connection with the fluidization to the top of the fluidized bed so as to be removed as a concentrate without a significant amount of the bed material and/or the heat transfer material escaping with the cured biocarbon product. By adjusting the fluidization rate close to the minimum fluidization rate of the bed material, the separation of the biocarbon product form the mixture may be en-hanced. In one embodiment also mechanical screening or centrifugal force may be utilized in order to separate the cured biocarbon. product. Magnetic separation may be used with magnetic materials, e.g. the heat trans-fer material. In one embodiment a separator may be provided either in the fluidized-bed reactor or there-after in order to separate the biocarbon product from the heat transfer material and/or the bed material. In one embodiment part of the separated biocarbon product is returned to the bottom of the fluidized-bed reac-tor.
In one embodiment of the invention the bio-based raw stock is selected from the group of: wood, wood-based raw stock, straw, different herbaceous bio-masses, biosludge, other solid biomass materials and other types of bio-based raw stock and their combina-tions. In addition to the fraction that is undesired for the production of the bio-based raw stock and es-pecially biocarbon, it is possible to burn in the com-bustion boiler peat, lignite, wood, waste materials and/or equivalent raw stock. The combustion boiler produces energy for the fluidized-bed reactor, e.g.
from the undesired raw stock and/or other starting ma-terials.
In one embodiment of the invention the bio-based raw stock is heated in the fluidized-bed reactor with a dwell time of less than 30 minutes, more pref-erably less than 20 minutes, and most preferably less than 5 minutes, in order to form a solid biocarbon product. By the present invention, even a dwell time of less than 5 min is reached instead of the dwell time of 20 to 30 min of the conventional shaft kilns.
This implies smaller and less expensive fluidized-bed reactors for the production of biocarbon. In addition,, the dwell time may be influenced by the particle size of the feed. For example, for the homogeneous carboni-zation of wood it is required that the inner part of the woodchip particle reaches the desired end tempera-ture. The temperature profile of the particle on its surface and inside of it may be described as a func-tion of the particle size and the heat-transfer coef-ficient.
In one embodiment the bio-based raw stock is crushed to a desired particle size before it is fed to the fluidized-bed reactor.
In one embodiment of the invention the bio-based raw stock is dried before producing the biocar-bon product, preferably with energy obtained from the combustion boiler and/or by energy fractions, e.g.
combustion gas or steam, or by the combustion gas de-veloped in the process using direct or indirect trans-fer of heat.
The drying of the bio-based raw stock may be performed in the fluidized-bed reactor designated for the production of biocarbon or in a separate reactor or drier. When the raw stock is dried in a separate drier, the evaporated water is separated from the product flow of the drier, e.g. in a cyclone, and the dried bio-based raw stock is thereafter fed to the fluidized-bed reactor in order to produce biocarbon.
The fluidized-bed reactor and the drier may be con-nected in series. Depending on the temperature used in the drier, the odorous gases may be burnt in the com-bustion boiler. In one embodiment the bio-based raw stock is dried by mixing it with heated heat transfer material or bed material of the fluidized-bed reactor before leading the mixture to the production of bio-carbon.
Production, i.e. a production step, of biocar-bon or a biocarbon product means in this context spe-cifically treatment of the bio-based raw stock in the fluidized-bed reactor in order to form a biocarbon product.
In one embodiment of the invention the bio-based raw stock is washed before producing the biocar-bon product in order to lower the ash content. In one embodiment ECN Torwash technology may be utilized in washing the raw stock. In this case, the bio-based raw stock, e.g. herbaceous biomass, may be washed by steam/hot water of the combustion boiler, whereupon 80 to 90 % of the problematic ash components may be re-duced. The reduction is lower with logging waste. In an alternative embodiment the raw stock may be washed by a hot water washing.
In one embodiment of the invention the appara-tus includes sorting means for the bio-based raw stock.
By the invention, the best raw stock may be sorted for the production of biocarbon and the undesired raw stock may be sorted for burning in order to form en-ergy. The integrated connection of the fluidized-bed reactor to the combustion boiler, e.g. a combustion boiler of the power station, gives a possibility to classify the biomaterial coming to the station accord-ing to the ash content or the content of harmful mate-rials. The intention is to lead only the low-ash, low-alkali and low-chlorine raw stock to the production of biocarbon. Correspondingly, the less favorable and un-desired fraction of the bio-based raw stock, e.g. the needles, the bark and the equivalent, may be led di-rectly to the combustion boiler for the production of energy.
In one embodiment the apparatus includes a classifier in order to sort the bio-based raw stock into a desired and undesired fraction in terms of the production of biocarbon. By the classifier, the de-sired fraction is guided to the production of biocar-bon and the undesired fraction is guided to the com-bustion boiler. The operation of the classifier may be based on density, mechanical screening, color differ-ence measurement or determination of the chemical com-position, e.g. on an NIR infra-red detector. The clas-sifier provides for the production of different bio-carbon grades from different kinds of raw stock ac-cording to the end use requirements of the biocarbon.
Typically, in power stations that use carbon and have high primary steam values, high ash, alkali or chlo-rine contents are not allowed.
In one embodiment of the invention the resid-ual and/or minor flows formed in the production of the biocarbon product are burnt in the combustion boiler in order to produce energy fractions. The odorous gases and other residual flows of the process may be burnt in the combustion boiler. Preferably, energy fractions are fed from the combustion boiler to the fluidized-bed reactor in the form of the heat transfer material, steam, heat and/or electricity.
In the production of biocarbon, water vapor as well as organic compounds and gases that are evap-orable at a low temperature evaporate from the bio-based raw stock, e.g. wood. The heat based on conden-sation of the gases may be recovered, e.g. to district heating water or steam circuit of the boiler, and/or the gas flow may be led to the combustion boiler to be burnt. This way, possible odor problems are avoided.
In addition, valuable chemicals may be utilized from the condensate.
In one embodiment of the invention the solid biocarbon fraction that has been formed is treated further by pelletizing, e.g. graining, granulating or in an equivalent manner, in order to form a biocarbon product. In one embodiment the biocarbon fraction is pelletized using a binder.
In one embodiment of the invention binders and/or additives, e.g. materials that ameliorate the weatherproofness, are added to the biocarbon product that has been formed in order to provide the final biocarbon product. In one embodiment suitable binders are added to biocarbon for binding the ash compounds that cause corrosion or scorification and/or in order to form pellets. Before pelletizing the biocarbon to form a biocarbon product, additives that ameliorate the weatherproofness of the product, such as olefine plastics that are unqualified for recycling, e.g. from package waste, may be added to the biocarbon in addi-tion to the optional binder. It is also possible to add e.g. lime to the biocarbon product for desulphuri-zation of the power stations.
In one embodiment the fluidized-bed reactor is selected from the group of reactors based on a s-pouted bed and a bubbling bed and their different com-binations, where the heavier bed material may be re-moved, if desired, from the bottom of the bed, and the lighter biocarbon may be removed as overflow from the top of the reactor. The cured biocarbon product may be circulated either in the internal circulation (spouted bed) or external circulation (bubbling bed) of the fluidized-bed reactor in order to control the dwell time of the treatment.
The combustion boiler may be any kind of a boiler known per se, either a large size class power station boiler or a small combustion boiler. If it is a typical district heat producing unit, the seasonal variations of energy load are significant. Heat power would be available especially in the summer, in the time of low heat demand, for large-scale and in the winter for smaller-scale biocarbon production.
The apparatus according to the invention may be integrated in connection with a large power sta-tion, e.g. of over 50t/h, corresponding to a power station of 250MWpa, or in connection with a smaller combustion boiler,,e.g. in pellet factories.
The biocarbon product according to the inven-tion may be used in the production of heat energy, e.g. as a substituent for coal.

Important advantages are achieved by the proc-ess and the apparatus according to the invention in comparison with the prior art.
Thanks to the invention, biocarbon of a good quality may be formed cost-effectively. Thanks to the invention, it is possible to utilize different types of raw stock and raw stock components which may not have been utilized cost-effectively before.
By the invention, a substantially better transfer of heat and power density of the reactor are achieved in the production of biocarbon than in the known biocarbon production processes. In addition, the integration of biocarbon and the combustion boiler of-fers important advantages in the treatment and drying of raw stock as well as treatment of different resid-ual and minor flows. Additionally, higher efficiency is reached, because essentially all the minor flows can be utilized.
By the invention, energy products, such as en-ergy fractions, are provided as additional products cost-effectively and with low production costs. Alter-natively, different value added products, such as bio-carbon products, are simultaneously provided by the in-vention in addition to the principal energy products, which increases the cost-effectiveness of the process.
The process and the apparatus according to the invention are substantially less expensive in pro-duction costs than the known biocarbon production processes, and the obtained product is a granulated biocarbon fuel that is purer and richer in energy than before.

LIST OF FIGURES
Fig. 1 presents one process apparatus accord-ing to the invention as a schematic plan.

DETAILED DESCRIPTION OF THE INVENTION

In the following, the invention will be de-scribed by means of a detailed exemplary embodiment with reference to the accompanying figure 1.

Example 1 This example describes the production of a biocarbon product by the process according to the in-vention and the apparatus according to Fig. 1. The in-tegrated process and apparatus presented herein are used in order to produce a biocarbon product and energy fractions at the same time.
The apparatus of Fig. 1 includes a fluidized-bed reactor 1 for the production of biocarbon and a combustion boiler.2 for the production of energy frac-tions and warming up and purifying of heat transfer material, these two being integrated together. Fur-thermore, the apparatus includes a classifier 3 for bio-based raw stock in order to sort the bio-based raw stock in terms of the production of biocarbon into a desired 18 fraction, e.g. wood pieces, woodchips and dust, and undesired 19 fraction, e.g. bark and needles, as well as feeding means (not presented in the figure) in order to feed the desired fraction 18 of the raw stock to the fluidized-bed reactor 1 and feeding means (not presented in the figure) in order to feed the un-desired fraction 19 to the combustion boiler 2. The apparatus includes a drier 5, wherein the fraction of the bio-based raw stock selected for the production of biocarbon is dried by hot combustion gases 16 to the moisture of approximately 10 to 15 % at a temperature of 40 to 100 C before feeding the raw stock to the fluidized-bed reactor 1. The bio-based raw stock may also be washed, if desired, before the production of the biocarbon product in order to lower.the ash con-tent.

In addition, the apparatus includes means for leading a heat transfer material 6 that has been hea-ted in the combustion boiler from the combustion boi-ler 2 to the fluidized-bed reactor 1. In this appara-tus the heated heat transfer material 6 is led to the raw stock 18 selected for the production of the bio-carbon product in the fluidized-bed reactor, i.e. to be in contact with the raw stock, in order to provide direct transfer of heat from the heat transfer mate-rial to the raw stock. In the fluidized-bed reactor 1 the raw stock 18 is heated by the heat transfer mate-rial 6 in oxygen-free conditions to a temperature of 220 to 350 C in order to form a solid biocarbon prod-, uct. In the fluidized-bed reactor there may be fluid-ized-bed sand in addition to the heat transfer mate-rial in order to form the fluidized bed, or alterna-tively the heat transfer material may act alone as the fluidized-bed material, forming the fluidized bed.
The apparatus includes a separator cyclone 4 in order to separate the biocarbon product 9 and 10 from the heat transfer material 7 and the fluidized-bed material 8 after the formation of the biocarbon product. Part of the separated biocarbon product 9 is returned to the bottom of the fluidized-bed reactor 1.
The rest of the biocarbon 10 is led to pelletizing in order to form biocarbon pellets, wherein binders and desired additives may be added to the biocarbon prod-uct. In addition, the apparatus includes means for circulating the heat transfer material 7 back to the combustion boiler 2 in order to heat and purify the heat transfer material.
A desired type of raw stock 17 may be fed to the combustion boiler 2 in addition to the fraction 19 rejected from the production of biocarbon in order to form energy fractions. In addition, a possibility to feed air to the combustion boiler (not presented in the figure) may be provided in the combustion boiler.
From the separator cyclone- 4, the combustion gases 11 are circulated via a filter 12 to the combus-tion boiler 2 as a combustion gas flow 13 in order to form energy fractions, to the fluidized-bed reactor 1 as a combustion gas flow 15 and/or to the drier 5 as a combustion gas flow 16 in order to dry the raw stock, and/or are led out of the process 14.

The process and the apparatus according to the invention are applicable in different embodiments for use in the production of most different types of bio-carbon products from most different types of raw stock.
The invention is not limited merely to the examples referred to above; instead, many variations are possible within the scope of the inventive idea defined by the claims.

Claims

1. A process for producing a biocarbon prod-uct from bio-based raw stock, characterized in that the bio-based raw stock is sorted by removing in the raw stock the fraction that is undesired in terms of the production of biocarbon from the desired fraction of the raw stock which is used for the pro-duction of biocarbon, the desired fraction of the raw stock is fed to a fluidized-bed reactor, the undesired fraction of the raw stock is fed to a combustion boiler disposed in connection with the fluidized-bed reactor in order to produce energy fractions, a heat transfer material to be used in the fluidized-bed re-actor is warmed up in the combustion boiler and the warmed-up heat transfer material is led to the fluid-ized-bed reactor, the bio-based raw stock is heated in the fluidized-bed reactor in oxygen-free conditions to a temperature of 220 to 350 °C in the presence of the heat transfer material in order to form a solid bio-carbon product, and the heat transfer material is cir-culated from the fluidized-bed reactor to the combus-tion boiler in order to warm up the heat transfer ma-terial.

2. The process according to claim 1, characterized in that the heat transfer mate-rial is led into contact with the bio-based raw stock in the fluidized-bed reactor.

3. The process according to any one of claims 1 to 2, characterized in that the heat transfer material is led to a heat exchanger provided inside the fluidized-bed reactor.

4. The process according to any one of claims 1 to 3, characterized in that the heat transfer material is separated from the biocarbon prod-uct that has been formed and circulated to the combus-tion boiler.

5. The process according to any one of claims 1 to 4, characterized in that the bio-based raw stock is chosen from the group of: wood, wood-based raw stock, straw, herbaceous biomasses, biosludge, other solid biomass materials and other types of bio-based raw stock and their combinations.

6. The process according to any one of claims 1 to 5, characterized in that the bio-based raw stock is heated in the fluidized-bed reactor with a dwell time of less than 5 minutes in order to form a solid biocarbon product.

7. The process according to any one of claims 1 to 6, characterized in that the bio-based raw stock is dried before the production of the biocar-bon product.

8. The process according to any one of claims 1 to 7, characterized in that the bio-based raw stock is washed before the production of the bio-carbon product in order to lower the ash content.

9. The process according to any one of claims 1 to 8, characterized in that the residual fractions and/or by-products formed in the production of the biocarbon product are burnt in the combustion boiler in order to produce energy fractions.

10. The process according to any one of claims 1 to 9, characterized in that energy frac-tions are fed from the combustion boiler to the fluid-ized-bed reactor in the form of the heat transfer mate-rial, steam, heat and/or electricity.

11. The process according to any one of claims 1 to 10, characterized in that the solid biocarbon product fraction that has been formed is treated further by pelletizing.

12. The process according to any one of claims 1 to 11, characterized in that binders and/or additives are added to the biocarbon product that has been formed.

13. An apparatus for producing a biocarbon product from bio-based raw stock, character-ized in that the apparatus includes a fluidized-bed reactor (1) in order to produce a biocarbon product and a combustion boiler (2) in order to produce energy fractions and warm up a heat transfer material, these two being integrated together, and sorting means (3) for the bio-based raw stock in order to sort the bio-based raw stock into a desired (18) and undesired (19) fraction in terms of the production of biocarbon, feed-ing means in order to feed the desired fraction (18) of the raw stock to the fluidized-bed reactor (1) and feeding means in order to feed the undesired fraction (19) of the raw stock to the combustion boiler (2), means for leading the warmed-up heat transfer material (6) from the combustion boiler to the fluidized-bed re-actor, means for separating the heat transfer material from the biocarbon product (10) that has been formed, and means for circulating the heat transfer material (7) back to the combustion boiler (2) in order to warm up the heat transfer material.

14. The apparatus according to claim 13, characterized in that the apparatus includes a separator device (4) in order to separate the heat transfer material (7) from the biocarbon product (10).

15. The apparatus according to claim 13 or 14, characterized in that the apparatus includes drying means (5) in order to dry the bio-based raw stock (18) before the production of the biocarbon prod-uct.

16. The apparatus according to any one of claims 13 to 15, characterized in that the apparatus includes means for leading the heat transfer material (6) to the bio-based raw stock (18) in the fluidized-bed reactor (1).

17. The apparatus according to any one of claims 13 to 16, characterized in that the apparatus includes a heat exchanger device provided in-side the fluidized-bed reactor (1) for leading the heat transfer material (6) therein in order to transfer heat from the heat transfer material (6) to the bio-based raw stock (18).

18. The apparatus according to any one of claims 13 to 17, characterized in that the ap-paratus includes means for leading residual and minor flows to the combustion boiler (2) in order to be burnt and to produce energy fractions.

19. The apparatus according to any one of claims 13 to 18, characterized in that the ap-paratus includes means (4,12) for separating and circu-lating the combustion gases (11).