FIELD OF THE INVENTION

The present invention relates to an integrated pyrolysis process. More particularly the process provides biomass pyrolysis in the presence of a reducing agent for converting biomass to low oxygen pyrolysis products, wherein pyrolysis is integrated with heat generation. The present invention relates also to a method for producing pyrolysis products. The invention further relates to the use of a reducing agent that is capable of removing oxygen, as a heat transfer material in transferring heat to pyrolysis reactor from a fluidized bed boiler.

BACKGROUND OF THE INVENTION

Pyrolysis oils are obtained using various feeds, methods and processes. Biomass pyrolysis represents thermochemical processing for producing pyrolysis oil, which may be used as heating fuel or it may be further converted to liquid transportation fuels and commodity chemicals.

Pyrolysis is generally understood as the chemical decomposition of organic materials by heating in the absence or with limited supply of oxidizing agent such as air or oxygen. Commercial pyrolysis applications are typically either focused on the production of charcoal (slow pyrolysis) or production of liquid products (fast pyrolysis), the pyrolysis oil.

Fast pyrolysis is used currently on commercial scale for producing pyrolysis oil, with up to 70 % liquid product yields. In fast pyrolysis solid biomass is thermally treated at the temperature typically ranging from 300 to 900°C, and the residence time of biomass in the pyrolyzer can be from a fraction of a second to seconds.

Pyrolysis oils are complex mixtures of chemical compounds typically containing oxygen, including reactive aldehydes and ketones. Said reactive compounds react with each other whereby complex molecules having higher molecular weight are formed and the viscosity of the pyrolysis oil is increased . For example, biomass derived pyrolysis oil typically comprises water, light volatiles and non-volatiles. Further, pyrolysis oil has high acidity, which typically leads to corrosion problems, substantial water content, and high oxygen content. Wood-based pyrolysis oil is the product of pyrolysis of wood or forest residues and it contains typically carboxylic acids, aldehydes, ketones, carbohydrates, thermally degraded lignin, water, and alkali metals. The oxygen-containing compounds (typically 40-50 wt%) and water (typically 15-30 wt%) make pyrolysis oils chemically and physically unstable. Although pyrolysis oils have higher energy density than wood, they are acidic (pH~2) and incompatible with conventional fuels. Furthermore these pyrolysis oils have high viscosity and high solid content.

Refining of pyrolysis oils to provide fuel or fuel components is often very challenging due to high oxygen content and the complex mixture of components of said bio-oil. For example pyrolysis oil typically consists of about 1500 compounds, most of which are still unidentified. Said compounds require very different conditions for converting them further to fuel components or precursors to fuel. Often this is carried out by hydroprocessing said pyrolysis oil over a catalyst capable of performing hydroprocessing reactions in the presence of hydrogen. Since pyrolysis oil typically contains even up to 50 wt% of oxygen, complete removal of oxygen from pyrolysis oil requires a substantial amount of external hydrogen, even 1000 L/kg pyrolysis oil. The obtained light components are turned into gaseous products (hydrogen, methane, ethane, etc.), and heavy components are turned into coke and heavy oil. The heavy oil mixture needs further refinement to produce fuel fractions and this procedure requires high amounts of hydrogen and typically various different catalysts for obtaining the desired products.

Different alternatives have been studied for improving the pyrolysis process, such as catalytic fast pyrolysis, catalytic pyrolysis in the presence of hydrogen, catalytic upgrading of the pyrolysis vapors, etc. Chemical looping combustion (CLC) is a concept for capturing carbon dioxide from systems generating heat and/or power. CLC produces flue gas comprising essentially pure C0 ₂ and water vapor.

Despite the ongoing research and development relating to bio-oils, there is still a need to provide improved pyrolysis processes. SUMMARY OF THE INVENTION

An object of the invention is to provide an improved pyrolysis process.

Another object of the invention is to provide a method for producing pyrolysis products.

Another object of the invention is to provide an integrated pyrolysis process where pyrolysis is integrated with heat generation.

Another object of the invention is to provide an integrated process where the content of oxygen containing compounds in the obtained pyrolysis oil can be decreased.

Another object of the invention is to provide an integrated process where pyrolysis oil and heat can be produced effectively, economically and in an environmentally sustainable way.

The present invention relates to an improved pyrolysis process.

Particularly, the invention relates to an integrated pyrolysis process, wherein the process comprises the steps, where

feedstock comprising biomass is pyrolyzed in a fluidized bed pyrolysis reactor in the presence of a heat transfer material comprising a solid reducing agent in reduced form to produce pyrolysis products, char and heat transfer material comprising the reducing agent in oxidized form,

the pyrolysis products are separated from the char and heat transfer material comprising the reducing agent, and the pyrolysis products are directed to a condenser where pyrolysis oil is separated from non-condensable gases, and the char and heat transfer material comprising the reducing agent are directed to a fluidized bed boiler,

fuel is fed to the fluidized bed boiler and combusted with the char in the presence of the heat transfer material comprising the reducing agent in oxidized form to produce heat, flue gas and heat transfer material comprising the reducing agent in the reduced form, and the heat transfer material comprising the reducing agent in the reduced forms conducted to the fluidized bed pyrolysis reactor.

The present invention also provides pyrolysis oils obtainable by said process. The present invention further provides the use of a reducing agent that is capable of removing oxygen, as a heat transfer material in transferring heat to pyrolysis reactor from a fluidized bed boiler. The present invention further provides the use of a reducing agent for removing oxygen from pyrolysis products in an integrated process comprising a fluidized bed boiler and a pyrolysis reactor wherein the reducing agent acts as a heat transfer material transferring heat from the fluidized bed boiler to the pyrolysis reactor. The present invention also provides a method for producing pyrolysis products wherein the method comprises

pyrolyzing feedstock comprising biomass in a fluidized bed pyrolysis reactor in the presence of a heat transfer material comprising a solid reducing agent in reduced form to produce pyrolysis products, char, and heat transfer material comprising the reducing agent in oxidized form,

separating the pyrolysis products from the char and heat transfer material comprising the reducing agent, and directing the char and heat transfer material comprising the reducing agent to a fluidized bed boiler,

directing the pyrolysis products to a condenser where pyrolysis oil is condensed and separated from non-condensable gases,

feeding fuel to the fluidized bed boiler and combusting it with the char in the presence of the heat transfer material comprising the reducing agent in oxidized form to produce heat, flue gas and heat transfer material comprising the reducing agent in the reduced form, and

- conducting the heat transfer material comprising a metal oxide to the fluidized bed pyrolysis reactor.

Characteristic features of the invention are presented in the appended claims. DEFINITIONS

The term "heat transfer material" refers here to material capable of carrying heat energy, particularly heat energy carrying particles, granules, etc.

The term "solid" refers here to a state of matter, which is characterized by structural rigidity and resistance to changes of shape or volume. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic flow diagram representing one embodiment of the process.

DETAILED DESCRIPTION OF THE INVENTION

In the present invention pyrolysis oil and heat are produced in an integrated process, where the heat may further be converted to power, steam etc. In the integrated process feedstock comprising biomass is pyrolyzed in a pyrolysis reactor with a solid reducing agent (oxidation-reduction chemical) in reduced form whereby char, pyrolysis products and used (oxidized) reducing agent containing oxygen are obtained. The pyrolysis products comprise vapors and gases. The pyrolysisi products are separated from the oxidized reducing agent and char. The oxidized reducing agent and char are directed to a boiler, where the char is combusted together with the fuel fed to the boiler and with oxygen contained in the reducing agent in oxidized form, whereby heat (heat energy) and flue gas comprising CO, C0 ₂ and N ₂ are produced, and simultaneously the boiler acts as an reduction reactor where the used reducing agent is reduced with the char and the boiler fuel. The reduced reducing agent is recycled or looped from the boiler to the pyrolysis reactor.

Accordingly, the invention relates to an integrated pyrolysis process. Said integrated pyrolysis process comprises the steps, where

feedstock comprising biomass is pyrolyzed in a fluidized bed pyrolysis reactor in the presence of a heat transfer material comprising a solid reducing agent in reduced form to produce pyrolysis products, char and heat transfer material comprising the reducing agent in oxidized form,

the pyrolysis products are separated from the char and heat transfer material comprising the reducing agent, and the pyrolysis products are directed to a condenser where pyrolysis oil is separated from non-condensable gases, and the char and heat transfer material comprising the reducing agent are directed to a fluidized bed boiler,

fuel is fed to the fluidized bed boiler and combusted with the char in the presence of the heat transfer material comprising the reducing agent in oxidized form to produce heat, flue gas and heat transfer material comprising the reducing agent in the reduced form, and the heat transfer material comprising the reducing agent in the reduced forms conducted to the fluidized bed pyrolysis reactor. In the process a pyrolysis reactor integrated with a boiler is utilized. The hot heat transfer material comprising the solid reducing agent is recycled or looped from the boiler to the pyrolysis reactor, where said reducing agent removes oxygen from the feedstock comprising biomass in oxidation-reduction reactions, and directs the radical reactions in said pyrolysis reactor whereby compounds comprising less oxygen are obtained. Said hot heat transfer material comprising the reducing agent is also used for maintaining the necessary pyrolysis temperature in the pyrolysis reactor.

In the integrated process fuel is fed to the boiler, where said fuel is combusted to provide flue gas and thermal energy, which can be converted to electricity, stream etc. Any fuels suitable for use in fluidized bed boilers may be used including gases, solids, liquids and mixtures thereof, based on fossil and renewable materials, such as coal, peat, heavy fuel oils, liquid fuels, biomass, waste materials, etc and combinations thereof. Said gases may include natural gas, biogas, light-end of pyrolysis, non-condensable pyrolysis gases, etc. Renewable materials, such as solid , wood based materials, biomass, etc may suitably be used as main fuel in the boiler. Co-fuels may suitably be selected from gases and other listed fuels. The solid fuel may optionally be dried with methods known as such prior to feeding to the boiler. Suitably the flue gases may be used for providing necessary heat to drying. The boiler is suitably a fluidized bed boiler, where the fuel, char and non-condensed gas can be combusted, and heat transfer material, such as sand etc. is heated. Said fluidized bed boiler may be a circulating fluidized bed boiler, a bubbling fluidized bed boiler, a combination thereof or other fluidized bed boiler known as such. The boiler may be operated at conditions generally used in fluidized bed boilers, the temperature typically being from 700 to 1200°C. Reductive conditions are achieved during the combustion in said fluidized bed boilers and said conditions may be adjusted for example by arranging air flow to the boiler to a lower part (lower half) of the boiler. The air flow is adjusted to provide the oxygen/fuel ratio sufficiently low for achieving incomplete combustion, whereby reductive conditions are achieved. The amount of needed air is calculated on the basis of oxygen content in the reducing agent exiting the boiler. The fluidized bed boiler has an conduit, feed pipe or the like, for transferring the heat transfer material comprising the reducing agent in the reduced form to the pyrolysis reactor. Suitably a pneumatic system is used for transferring the heat transfer material from the boiler to the pyrolysis reactor. The conduit, feed pipe etc. is suitably arranged at the bottom of the fluidized bed boiler, at the side or at the top of the boiler depending on the boiler type (circulating fluidized bed, bubbling bed) and on the reductive conditions inside the boiler.

Figure 1 shows an embodiment of the integrated pyrolysis process. In an overview, the process is carried out in a pyrolysis reactor 300 integrated with a boiler 100.

Fuel 10 is fed to a fluidized bed boiler 100, where the fuel is combusted in the presence of heat transfer material comprising a solid reducing agent in oxidized form and char from the pyrolysis reactor 300, whereby heat energy and flue gases are formed and the reducing agent is reduced. Airflow 110 is conducted to the boiler for providing additional oxygen for combustion. The flue gas is divided into a first flue gas stream 20 and to second flue gas stream 21. The stream 80 comprising the heat transfer material comprising the reducing agent in oxidized form and char separated from the pyrolysis output 40 is supplied to the fluidized bed boiler 100 from a solid/vapor separator 500.

Feedstock comprising biomass 30 is fed to the pyrolysis reactor 300 and the heat transfer material comprising the reducing agent in reduced form 90 is delivered from the boiler 100 via conduit 200 to the pyrolysis reactor 300. The second flue gas stream 21 is directed to the conduit 200, where further reduction of the reducing agent is carried out with CO contained in the flue gas stream 21. The flue gas stream 21 can also be fed as fluidizing gas to the pyrolysis reactor 300. The feedstock is pyrolyzed in the pyrolysis reactor 300 in the presence of the heat transfer material comprising the reducing agent 90, whereby pyrolysis output 40 is obtained. The pyrolysis output 40 comprises pyrolysis vapors, gases and char and heat transfer material comprising the reducing agent (solids). The pyrolysis output 40 is directed to a solids/vapor separator 500, suitably a cyclone, where solids comprising char and heat transfer material comprising the reducing agent are separated and recycled to the boiler 100 as stream 80, and the gases and vapors are directed as stream 50 to a condenser 400 where the pyrolysis oils are condensed. As an output from the condenser pyrolysis liquid 60 and non-condensable gases 70 are obtained. Optionally the pyrolysis liquid 60 may be directed to hydroprocessing system 600 comprising necessary equipment and materials for carrying out catalytic hydroprocessing reactions, to obtain hydrocarbons boiling in the diesel range 61, hydrocarbons boiling in the gasoline range 62 and hydrocarbons boiling in the jet fuel range 63. The inlets of the air flow, fuel, heat transfer material to the boiler and the outlet of the heat transfer material may be selected according to the boiler configuration.

During the start-up of the process the heat transfer material comprising fresh reducing agent in oxidized form is treated in the boiler first. In the case the fresh reducing agent is in reduced form it may be directed straight to the pyrolysis reactor.

The heat transfer material comprises 20-100 wt%, preferably 50-100 wt% of the solid reducing agent. According to one embodiment the heat transfer material comprises 20-80 wt% of the reducing agent. The heat transfer material may further comprise 0- 80 wt% inert particulate material suitable as heat transfer material. An example of such inert material is sand.

The heat transfer material comprising the reducing agent is recycled or looped from the boiler to the pyrolysis reactor, and from the pyrolysis reactor, via a solids/vapor separator to the boiler.

The pyrolysis is carried out as fast pyrolysis, suitably in a fluidized bed reactor, such as a circulating fluidizing bed reactor, a bubbling bed fluidizing bed reactor, a combination thereof or the like.

The pyrolysis is suitably carried out at the temperature of 200-900°C, more suitably 200-750°C, and even more suitable 300-700°C.

The heat transfer material is typically used for heating the feedstock particles.

The residence time of the feedstock (transported through the reactor) is typically 0.1 - 200 s, suitably 0.1 - 10 s, particularly suitably 0.1 - 5 s.

The pyrolysis is suitably carried out under the pressure of 0.1-20 bar, more suitably 0.1-10 bar.

A pyrolysis product comprising gases and vapors is obtained from the pyrolysis.

The formed pyrolysis vapors are condensed to obtain pyrolysis oil, and the non- condensable gases are separated. According to one embodiment the non-condensable gases are recycled to the boiler where light hydrocarbons contained therein are combusted and used as additional fuel.

Feedstock comprising biomass is subjected to pyrolysis. The biomass may comprise a wide variety of materials of biological origin. Biomass may typically comprise virgin and waste materials of plant, animal and/or fish origin or microbiological origin, such as virgin wood, wood residues, forest residues, waste, municipal waste, industrial waste or by-products, agricultural waste or by-products (including also dung or manure), residues or by-products of the wood-processing industry, waste or byproducts of the food industry, solid or semi-solid organic residues of anaerobic or aerobic digestion, such as residues from bio-gas production from lignocellulosic and/or municipal waste material, residues from bio-ethanol production process, and any combinations thereof. Biomass may include the groups of the following four categories: wood and wood residues, including sawmill and paper mill discards, municipal paper waste, agricultural residues, including corn stover (stalks and straw) and sugarcane bagasse, and dedicated energy crops, which are mostly composed of tall, woody grasses.

Suitably the biomass is selected from material originating from non-edible sources such as non-edible wastes and non-edible plant materials. Particularly suitably said biomass comprises waste and by-products of the wood-processing industry such as slash, urban wood waste, lumber waste, wood chips, wood waste, sawdust, straw, firewood, wood materials, paper, by-products of the papermaking or timber processes, where the biomass (plant biomass) is composed of cellulose and hemicellulose, and lignin.

The biomass feedstock may be subjected to size reduction or particularization prior to feeding to the pyrolysis reactor to provide size of the biomass for heat transfer rates suitable for maximal oil production. Any suitable grinder etc. may be used. The biomass feedstock may be subjected to drying for reducing the moisture content therein prior to feeding to the pyrolysis reactor. Suitably the moisture content may be reduced to not more than 15 wt%, more suitably not more than 10 wt%, or even not more than 5 wt%, on dry weight basis. Drying of the biomass reduces char formation. Any driers suitable for drying of biomass can be used, such as drum driers, flash driers, fluidized bed driers etc., where drying may be carried out with a drying gas. Hot flue gas obtained from the boiler is suitably used as the drying gas. The heat transfer material comprising the solid reducing agent in the reduced form is conducted from the boiler using a conduit, transfer pipe etc, suitably arranged at the lower half of the boiler, to the fluidized bed pyrolysis reactor, suitably to an inlet at the lower half, particularly suitably arranged at the bottom of the pyrolysis reactor. In said pyrolysis reactor the heat transfer material is carried with the fluidizing fluid to the outlet of the reactor, suitably at the top of reactor, wherefrom it is directed to a solids/vapor separator, such as a cyclone. In said solids/vapor separator solid particles are separated from the vapors and gaseous components, said solid particles comprising char and the heat transfer material, which comprises the reducing agent in the oxidized form.

The fluidizing fluid may be selected from inert gases and gas mixtures typically used in pyrolysis. According to one suitable embodiment the flue gas from the boiler is used as the fluidizing fluid in the pyrolysis reactor. Optionally the flue gas may be mixed with inert gases and gas mixtures.

According to one suitable embodiment the flue gas from boiler is divided into a first and a second flue gas stream, the second flue gas stream is combined with the heat transfer material comprising the reducing agent in reduced form, exiting from the boiler and the combined heat transfer material and the flue gas are conducted to the fluidized bed pyrolysis reactor. The second flue gas stream comprising CO acts as a supplemental reducing agent and also provides for the fluidizing fluid needed in the pyrolysis reactor. According to one suitable embodiment the flue gas from the boiler is conducted via a pipe and an inlet to the conduit, transfer pipe etc which transfers the hot heat transfer material comprising the reducing agent from the boiler to the pyrolysis reactor. According to one embodiment the flue gas may be used for drying of the biomass feedstock.

According to one embodiment the flue gas may be used for drying of the solid feed to the boiler. The solid reducing agent comprises a metal redox compound which is reduced to a lower oxidation state than the maximum oxidation state of said metal, at conditions prevailing in the boiler, and which is oxidized to a higher oxidation state under conditions prevailing in the pyroiysis reactor. This means that the metal redox compound may be in partly reduced form after boiler treatment and in partly oxidized form after the pyroiysis.

The solid reducing agent is selected from materials comprising one or more metals selected from Fe, Sn, Cr, Ni, Mn, Co, Ni, Mo, Cu, W. Suitable materials are metal oxides and minerals comprising metal oxides. Suitably said metal oxides have redox properties at the reduction and oxidation conditions of the present process. Suitably the metal oxide is a metal oxide of Fe, Sn, Cr, Ni, Mn, Co, Ni, Mo, Cu, W, a mixed oxide of said metals, a mixed oxide of said metals with other metals or nonmetals, or a combination of said oxides. Suitably the mineral comprises an oxide of Fe, Sn, Cr, Ni, Mn, Co, Ni, Mo, Cu, W, mixed oxide of said metals, mixed oxide of said metals with other metals or nonmetals, or a combination of said oxides oxide, preferably of iron or manganese. Examples of such minerals are ilmenite, hematite, magnetite and pyrolusite. According to one embodiment oxides of Ni, Cu, Mn or Fe are used.

The reducing agent acts as a reactant in the pyroiysis process. The oxidation state of the metal is changed in the redox cycle in the process. After the reduction the metal is in reduced state. For example, in the reduced state the oxidation state of Ni is 0, and after oxidation at pyroiysis the oxidation state is increased to 2.

The reducing agent may optionally be on a support, such as alumina, silica, zirconia, sand etc. The reducing agent may optionally be in the form of granules, particles etc. The granule size is selected according to the solid/vapor separator needs.

The reducing agent may replace traditional heat transfer materials in part or totally. The heat transfer material comprising the reducing agent carries heat from the boiler to the pyroiysis reactor, and the reducing agent acts as a reagent which removes oxygen from the biomass intermediates during pyroiysis.

The residence time of heat transfer material comprising the reducing agent, in the pyroiysis reactor is 0.8-2, suitably 0.9 - 1.5 times the residence time of the feedstock. The amount of the reducing agent in the pyrolysis step is adjusted according to the amount of oxygen contained in the biomass feed to the pyrolysis. Suitably at least 0.4, more suitably 0.4-15 mole ratio of the reducing agent is used with respect to the biomass oxygen content. When metals with higher oxidation state are used, less of the respective metal oxide is needed.

The low-oxygen content pyrolysis oil may directly be subjected to catalytic hydroprocessing for providing transportation fuels and other chemicals.

Said catalytic hydroprocessing may be carried out in one stage where hydrodeoxygenation (HDO) and hydrodewaxing (HDW), is carried out or in at least two stages, where in the first stage hydrodeoxygenation (HDO) is carried out and in the second stage hydroisomerization (HI) and/or hydrodewaxing (HDW) is carried out. The HDO catalyst can be any HDO catalyst known in the art for the removal of hetero atoms (O, S, N) from organic compounds. In an embodiment of the invention, the HDO catalyst is selected from a group consisting of NiMo, CoMo, and a mixture of Ni, Mo and Co. Suitably the HDO catalyst is a supported catalyst and the support can be any oxide, typically said oxide is selected from Al ₂ 0 ₃ , Si0 ₂ , Zr0 ₂ , zeolites, zeolite-alumina, alumina-silica, alumina-silica-zeolite and activated carbon, and mixtures thereof.

The HDO catalyst(s) is/are sulphided prior to start up. Adequate sulphidization during operation is usually provided by sulphur compounds contained in the feed material or by adding sulphur containing reagents to the process.

In an embodiment of the invention, the HDW catalyst is selected from hydrodewaxing catalysts typically used for isomerising and cracking paraffinic hydrocarbon feeds. Examples of HDW catalysts include catalysts based on Ni, W, and molecular sieves. NiW has excellent isomerising and dearomatising properties and it also has the capacity of performing the hydrodeoxygenation and other hydrogenation reactions of biological feed materials, which are typically performed by HDO catalysts. Aluminosilicate molecular sieves and especially zeolites with medium or large pore sizes are also useful as HDW catalysts in the present invention. Typical commercial zeolites useful in the invention include for instance ZSM-5, ZSM-11, ZSM-12, ZSM 22, ZSM-23 and ZSM 35. Other useful zeolites are zeolite beta and zeolite Y. The HDW catalyst is also supported on an oxide support. The support materials may be the same as or different from those of the HDO catalyst. In an embodiment of the invention the HDW catalyst is selected from NiW/AI ₂ 0 ₃ and NiW/zeolite/AI ₂ 0 ₃ . These HDW catalysts are especially well suited for combining with the HDO catalyst of the invention since they also require sulphidizing for proper catalytic activity.

In an embodiment of the invention, the HI catalyst is selected from hydroisomerizing catalysts typically used for isomerizing paraffinic hydrocarbon feeds. Suitably the HI catalysts contain a Group VIII metal (e.g. Pt, Pd, Ni) and/or a molecular sieve. Preferred molecular sieves are zeolites (e.g. ZSM-22 and ZSM-23) and silicoaluminophosphates (e.g. SAPO-11 and SAPO-41). HI catalysts may also contain one or more of the support materials described above. In one embodiment, the HI catalyst comprises Pt, a zeolite and/or silicoaluminophosphate molecular sieve, and alumina. The support may alternatively or additionally contain silica. Suitably sulphur is removed from the product obtained from the HDO step prior to hydroisomerization step utilizing these HI catalysts.

The main hydroprocessing products are paraffinic hydrocarbons in the Ci ₆ -C ₂ o range. The long carbon chains are isomerized, which improves the cold flow properties of the resulting fuel. The isomerisation takes place before, after or simultaneously with the hydrodeoxygenation due to the combination of HDO and HDW catalysts and the packing of the catalyst material. Olefins and aromatic compounds are hydrogenated and fused ring systems are broken. This reduces the complexity of the compounds and improves the quality of the fuel. Cracking of large molecules, side chains and of some of the long chains occurs, which results in an increase of smaller useful molecules but also causes an increase in light gaseous products (methane, ethane, propane and butane).

The amount of hydrogen gas needed for the various hydroprocessing reactions depends on the amount and type of the feed material. The amount of hydrogen required depends also on the process conditions.

In the catalytic hydroprocessing the hydrogen partial pressure is maintained in the range from 50 to 250 bar, suitably from 80 to 200 bar, particularly suitably from 80 to 110 bar. The total pressure in the hydroprocessing is from 50 to 250 bar, suitably from 80 to 120 bar. The hydroprocessing is carried out at a temperature in the range of 280°C to 450°C, suitably from 350°C to 400°C.

The hydroprocessing feed rate WHSV (weight hourly spatial velocity) of the feedstock is proportiona l to an amount of the catalyst. The WHSV of the feed material in the present invention varies between 0.1 and 5, a nd is preferably in the range of 0.3 - 0.7.

The ratio of H ₂ /feed in the present invention depends on feedstock qua lity and varies between 600 and 4000 Nl/I, suitably of 1300-2200 Nl/I .

According to one embodiment the process may be ca rried out in at least two sepa rate steps in at least two reactors. In the first step hydrodeoxygenation (HDO) is carried out and in the second step isomerization (HI) is carried out for branching the hydrocarbon chain.

The reaction product from HDO is subjected to an isomerization step. The impurities should be removed before the hydrocarbons are contacted with the isomerization catalyst. The isomerization and the HDO may be carried out in the same pressure vessel or in sepa rate pressure vessels.

The reaction mixture from the hydroprocessing reactor system is directed to a sepa rator, suitably cold separator, where water, the light component comprising hydrogen, light hydrocarbons (CI - C5 hydrocarbons), H ₂ S, CO and C0 ₂ are sepa rated from the heavy component comprising >C5 hydroca rbons and some CI - C5 hydrocarbons.

The liquid reaction products, i .e. the mixture of higher (> C5) hyd rocarbons may be subjected to fractionation. Suitably it is fed to a sepa ration column where different fuel grade hydrocarbon fractions are recovered . The liquid hydrocarbon mixture obta ined from the reactor system includes fuel grade hydrocarbons having a boiling point of at most 380°C according to ISO EN 3405. The person skilled in the art is able to vary the distilling conditions and to change the temperature cut point as desired to obta in any suitable hydroca rbon product. The recovered middle distillate fraction may comprise gas oil, i.e. a hydrocarbon fraction having a boiling point in the diesel range. A typical boiling point is from 160°C to 380°C, meeting characteristics of the specification of EN 590 diesel. The diesel product may be fed to a diesel storage tank. Also hydrocarbon fractions distilling at temperatures ranging from 40°C to 210°C and at a temperature of about 370 °C can be recovered. These fractions are useful as high quality gasoline fuel and/or naphtha fuel, or as blending components for these fuels. Additionally, fraction suitable as solvents, aviation fuels, kerosene, jet fuel, etc. may be obtained.

The integrated process provides several advantages. High quality pyrolysis oil obtained from the present process contains typically less than 10 wt% of oxygen, which is clearly less than the oxygen content in pyrolysis oils obtained with currently used pyrolysis processes, typically being from 30 to 50 wt%. Lower oxygen content requires less hydrogen in further hydroconversion reactions and makes the hydroprocessing easier, lower hydrotreatment pressures are needed, which are important advantages particularly in the cases where pyrolysis oil is further converted to transportation fuels. Lower oxygen content also provides improved heat of combustion.

The pH of the obtained pyrolysis oil is typically 4 or more, which is higher than the one of conventionally produced pyrolysis oils. This improves the long term and short term stability of the pyrolysis oil and causes less corrosion problems.

This low-oxygen content pyrolysis oil with improved stability may also be used as fuel in combustion apparatus suitable for such fuels.

The pyrolysis oil has typically lower viscosity, which makes the handling of it easier.

The oxygen carried by the solid reducing agent from the pyrolysis reactor to the boiler increases the amount of oxygen available for combustion in the boiler, which improves the combustion and more concentrated C0 ₂ is obtained from the boiler. This C0 ₂ can be readily captured and sequestered. However, the reducing agent is not only an oxygen carrier, it is also an oxygen scavenger reagent.

In the integrated process any standard fluidized bed boiler can be used as reducing environment for the reducing agent, where char and fuel are used for reducing the reducing agent. The boiler also provides the heat required for the pyrolysis reactor, and the energy of the non-condensable gases may also be utilized in the boiler, the flue gases from the boiler may be used as the fluidizing fluid in the pyrolysis reactor and as final reducing gas of the reducing agent. The combustion in the boiler is improved with additional oxygen provided by the recycled reducing agent, and the amount of C0 ₂ is increased in the flue gas, whereby the separation of it is easier.