FIELD OF THE INVENTION

The present invention relates to a biomass-based hydrotreatment system and a method of hydrotreatment of a fuel feed.

BACKGROUND OF THE INVENTION

Reducing an environmental impact of fuel products has seen increasing interest over the last years to limit the green house gas emissions linked to the present production methods. Hydrogen is used as an important element in upgrading both fossil as well as sustainable fuel feeds. As an example, hydrotreatment of fossil and non-fossil feed is conducted e.g. to remove oxygen content, lower acidity of the fuel or to adjust the heating value of the fuel.

A number of documents have been published in the field, such as US2013340322 and US2020255745. These disclosures generally show to separate char and pyrolysis gas, combusting the latter to generate heat and superheated steam to be used in a subsequent gasification process together with the char. However, this process is inefficient from an energy perspective due to energy losses in heat transfer equipment and due to an imbalance between the amount of steam produced and the amount char needed to achieve efficient gasification using said steam.

Hence, an improved method of hydrotreatment of fuel feeds would be advantageous, and in particular a method combining a fuel feed and a non-fossil hydrogen source i.e. , hydrogen produced from other sources than fossil fuel would be advantageous.

OBJECT OF THE INVENTION

It is an objective of the present innovation to overcome the presented limitations in the prior art. In particular, it is an objective to provide a method of hydrotreatment of a fuel feed by combining fossil or non-fossil fuel feeds with a hydrogen produced by means of hydrogen molecule yield-maximized gasification of biomass.

It is a further object of the present invention to provide an alternative to the prior art. SUMMARY OF THE INVENTION

Thus, the above-described object and several other objects are intended to be obtained in a first aspect of the invention by providing a method of hydrotreatment of a fuel feed. The method comprises providing a biomass feedstock and a fuel feed to be hydrotreated, and pyrolysing the biomass feedstock in a pyrolysis reactor to produce a pyrolysis gas (PG) and a solid pyrolysis char (PC). The method further comprises at least partially oxidizing the pyrolysis gas into a partially oxidized pyrolysis gas by providing an oxidizing gas, and gasifying the pyrolysis char in a gasification reactor using the partially oxidized pyrolysis gas to produce a synthesis gas (SG), wherein the synthesis gas has a high content of hydrogen molecules ( H ₂ ). Finally, the method comprises performing a hydrotreatment process on the fuel feed using the synthesis gas to produce a hydrotreated fuel feed. In this way, the hydrogen-rich synthesis gas resulting from the pyrolysis and subsequent gasification process of biomass may be directly used to improve the fuel feed via the hydrotreatment process. Improving the fuel feed is in this context understood to mean e.g. reducing an oxygen content, reducing a sulphur content, increase a hydrogen content, to crack hydrocarbons, to improve a quality of the fuel feed e.g. by increasing a heating value, changing a viscosity or a density, adjust a cetane number etc. or by removing components in the fuel feed. In other words, the hydrogen of biomass-origin may be used in hydrotreatment of fuel feeds of e.g. fossil or biomass origin, or a combination. This whole process may preferably take place onsite/in situ at a refinery performing the hydrotreatment (hereinafter also referred to as a hydrotreatment plant for brevity). In situ-production of hydrogen-rich synthetic gas for hydrotreatment has one or more of the following synergistic effects: - A reduced energy loss and/or energy consumption to compression and transportation of the H2 that may otherwise be needed for transporting hydrogen to the hydrotreatment process.

In conventional hydrotreatment plants, the pressure in the hydrotreatment process is generally achieved via heating the gas up in a pressure vessel. Excess heat from the gasifier may be exploited to deliver heat to the hydrotreatment process and achieve some portion of the required process pressure.

Since the pyrolysis gas contains both C02 and H20, heat from the pyrolysis step will lead to some conversion to CO and H2, even without otherwise providing an oxidizing gas from the outside. However, an oxidizing gas may also optionally be provided. Alternatively, the synthesis gas may be produced in another location and transported to the hydrotreatment plant for further use. The inventors have realized that pyrolysis and subsequent gasification of biomass is a sustainable and cost- efficient way of producing a green/non-fossil synthesis gas with a high content of hydrogen molecules (H2), or even pure hydrogen gas by way of subsequent separation processes.

In one embodiment, the partially oxidized pyrolysis gas is used directly to produce the synthesis gas.

In another embodiment, the partially oxidized pyrolysis gas is used as a source for heating another gasification agent, such as steam, C02, etc.

In a typical embodiment, the oxidizing gas is atmospheric air.

In another embodiment, the oxidizing gas is a bespoke mix of oxygen, carbon dioxide and/or steam, and other gaseous compounds, said gaseous compounds comprising less than 10%v. In this way, the hydrogen molecule yield of the synthesis gas is maximized.

In yet another embodiment, the oxidizing gas is a nitrogen content reduced atmospheric air.

The bespoke mix and nitrogen content reduced oxidizing gasses serve to maximize the fraction or amount of hydrogen molecules in the synthesis gas. In an embodiment of the method according to the invention, the content of hydrogen molecules in the synthesis gas is at least 10%v, such as at least 20%v, at least 30%v, at least 40%v, at least 50%v, or even higher. The ranges achieved are highly dependent on the selection of oxidizing gas and other process parameters.

In an embodiment of the method according to the invention, the hydrotreatment process is or comprises one or more of hydrocracking, hydrogenation, hydrodeoxygenation, or hydrodesulfurization. The latter three processes being instrumental in controlling important parameters of the hydrotreated fuel feed, in particular the carbon chain length, heating value, sulphur content and viscosity of the fuel feed. In an embodiment of the method according to the invention, the pyrolysis reactor and the gasification reactor are separate units. In this way, the different temperature ranges needed for the two processes may conveniently be achieved.

In an embodiment of the method according to the invention, the pyrolysis reactor and the gasification reactor is a combined unit comprising a pyrolysis zone and a gasification zone. In this way, the energy flow, in particular the heat flow, in the process may be utilized efficiently. Thus, an improved energy efficiency is achieved, compared to having separate processes.

In an embodiment of the method according to the invention, the partially oxidized pyrolysis gas is used as primary gasification agent to gasify the pyrolysis char. In this way, the pyrolysis gas produced may be directly used in the gasification process of the pyrolysis char.

In an embodiment of the method according to the invention, the partially oxidized pyrolysis gas is used in conjunction with at least one other gasification agent to gasify the pyrolysis char. In some embodiments, it is advantageous to use a combination of two or more gasification agents, whereof the partially oxidized pyrolysis gas is one.

In an embodiment of the method according to the invention, the at least one other gasification agent comprises steam.

In an embodiment of the method according to the invention, the fuel feed comprises a fossil oil feed or a partly fossil oil feed. In this way, a carbon intensity (Cl) score or green house gas (GHG) score of the hydrotreated fossil or partly fossil feed may be improved, by using the hydrogen-rich synthesis gas of biomass origin.

In an embodiment of the method according to the invention, the fuel feed comprises a non-fossil oil feed, such as a biomass derived oil. This method may also be used to improve a non-fossil oil by hydrotreatment. In some embodiments, the non-fossil oil is produced as part of the same pyrolysis and subsequent gasification process, more specifically from the pyrolysis-step of the process. In other embodiments, the non-fossil oil is received from another source.

According to a second aspect of the invention, the invention concerns a biomass- based hydrotreatment system, wherein the system comprises a pyrolysis reactor comprising a biomass feedstock inlet and a pyrolysis gas and char outlet, wherein the pyrolysis reactor is adapted for pyrolysis of a biomass feedstock into a pyrolysis gas and a pyrolysis char. The system further comprises a gasification reactor in communication with the pyrolysis gas and char outlet, the gasification reactor further comprising gas outlet, wherein the gasification reactor is adapted for gasification of the pyrolysis char using the pyrolysis gas, to produce a synthesis gas exiting the gasification reactor via the gas outlet. Finally, the system comprises a hydrotreatment reactor in communication with the gas outlet of the gasification reactor, the hydrotreatment reactor further comprising a fuel feed inlet for receiving a fuel feed and a fuel feed outlet, wherein the hydrotreatment reactor is configured for performing a hydrotreatment process on the fuel feed using the synthesis gas received via the gas outlet and for delivering the resulting fuel feed to the fuel feed outlet. In this way, a system is achieved that enables convenient production of synthesis gas from a biomass feedstock to be used for hydrotreatment of a fuel feed. The fuel feed may be of fossil or bio origin, or a combination.

In an embodiment of the system according to the invention, the pyrolysis reactor and gasification reactor comprised as a combined reactor, the combined reactor comprising a pyrolysis zone and a gasification zone.

In an embodiment of the system according to the invention, the pyrolysis reactor and gasification reactor separated by a oxidization zone, the oxidization zone being adapted for facilitating a partial oxidization of the pyrolysis gas into a partially oxidized pyrolysis gas, substantially before the partially oxidized pyrolysis gas reaches the gasification reactor. In this way, a majority of a content of tar in the pyrolysis gas is decomposed into gas, before or in the gasification reactor.

In an embodiment of the system according to the invention, the oxidization zone is comprised by the pyrolysis reactor. In an embodiment of the system according to the invention, the oxidization zone is comprised by the gasification reactor.

In an embodiment of the system according to the invention, the oxidization zone is comprised by a conduit connecting the pyrolysis reactor and the gasification reactor.

The first and second aspects of the present invention may be combined. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE FIGURES

The method of hydrotreatment and biomass-based hydrotreatment system according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set. Figure 1 is a flow-chart illustrating an embodiment of the method of hydrotreatment,

Figure 2 illustrates embodiments of pyrolysing the biomass feedstock and oxidizing the pyrolysis gas,

Figure 3 illustrates the gasifying step of the method, Figure 4 schematically illustrates an embodiment of the system according to the invention,

Figure 5 schematically illustrates another embodiment of the system according to the invention, and Figure 6 schematically illustrates other embodiments of the system according to the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT Figure 1 is a flow-chart illustrating an embodiment of the method of hydrotreatment 100. Initially, biomass feedstock is provided 102, such as residues from cultivating wheat, corn, sugar, tobacco, palm oil. The biomass feedstock is pyrolysed 104 in a pyrolysis reactor, to produce both a pyrolysis gas PG and a pyrolysis char PC. The pyrolysis gas PG is oxidized 106, at least partially, into a partially oxidized pyrolysis gas OPG by providing an oxidizing gas 107. The partially oxidized pyrolysis gas OPG is used to gasify 108 the pyrolysis char PC to produce a hydrogen-rich synthesis gas SG. Finally, the hydrogen-rich synthesis gas SG is used to perform a hydrotreatment 110 process on a fuel feed 112, in order to achieve an improved fuel feed 114. Figure 2a and 2b illustrates two embodiments of pyrolysing the biomass feedstock and gasifying the pyrolysis char. Figure 2a shows that pyrolysing 104 the biomass feedstock occurs in a pyrolysis reactor 202 that is separate from a gasification reactor 204 in which gasification 108 of the pyrolysis char PC takes place. Between the two reactors 202, 204, partial or full oxidation 106 of the pyrolysis gas occurs by providing an oxidizing gas 107. In figure 2b, the same processes of pyrolysis 104 and gasification 108 occurs, but in a combined reactor 206. In the reactor 206, pyrolysis 104 occurs in a pyrolysis zone 202’, while gasification 108 occurs in a gasification zone 204’. Since the pyrolysis gas contains both C02 and H20, the heat present in the combined reactor 206 will lead to some conversion to CO and H2, even without providing an oxidizing gas from the outside. However, an oxidizing gas 107 may also optionally be provided to the combined reactor 206 in this embodiment.

Figure 3a illustrates that the partially oxidized pyrolysis gas OPG is used as the primary gasification agent to gasify 108 the pyrolysis char PC, thus producing the synthesis gas SG. Figure 3b shows an embodiment wherein the partially oxidized pyrolysis gas OPG is used together with a second gasification agent 302 to gasify 108 the pyrolysis char PC and produce the synthesis gas SG.

Figure 4 illustrates an embodiment of the biomass-based hydrotreatment system 400 according to the invention, comprising a pyrolysis reactor 202, a gasification reactor 204, and a hydrotreatment reactor 402. The pyrolysis reactor 202 comprises a biomass feedstock inlet 404, a pyrolysis gas outlet 406, and a pyrolysis char outlet 408. The pyrolysis gas outlet 406 and the pyrolysis char outlet 408 are both connected as inlets to the gasification reactor 204. Optionally, a second gasification agent 302 may be injected in the gasification reactor 204. From the gasification reactor 204 a gas outlet 410 is connected as an inlet to the hydrotreatment reactor 402. Further indicated by the arrow 411 is the heat transfer from the gasification reactor 204 to the hydrotreatment reactor 402 as a result from the in situ gasification process. The hydrotreatment reactor 402 further comprises a fuel feed inlet 412. Finally, the hydrotreatment reactor 402 comprises an outlet 414 for the produced improved fuel feed.

Figure 5 shows another embodiment of the system 400 that relates to the embodiment shown in figure 4. Therefore, only the differences are discussed here.

In this embodiment, the pyrolysis reactor 202 and the gasification reactor 204 are provided as a combined reactor 206, having a pyrolysis zone 202’ and a gasification zone 204’. Otherwise, the processes are equivalent to the embodiment of figure 4.

Figure 6a and 6b illustrate different embodiments of the system 400, in particular different configurations of an oxidation zone 620.

The embodiment shown in figure 6a corresponds to that of figure 4, where like reference numerals refer to like parts. This embodiment differs by comprising an oxidation zone 620 between the pyrolysis reactor 202 and the gasification reactor 204. The oxidation zone 620 is configured to allow for partial or full oxidation of the pyrolysis gas received via the pyrolysis gas outlet 406 by use of an oxidizing gas 107, before passing on the partially oxidized pyrolysis gas via a partially oxidized pyrolysis gas inlet 406’ to the gasification reactor 204. The pyrolysis char passes from the pyrolysis reactor 202 via the pyrolysis char outlet 408, the oxidation zone 620, and pyrolysis char inlet 408’ to the gasification reactor 204 for subsequent gasification by use of the partially oxidized pyrolysis gas. The oxidation zone 620 may be provided as a separate oxidation reactor, or as part of conduits from the pyrolysis reactor 202 to the gasification reactor 204. The embodiment shown in figure 6b corresponds to that of figure 5, where like reference numerals refer to like parts. In this embodiment, the combined reactor 206 is further configured to provide an oxidation zone 620’ between the pyrolysis zone 202’ and the gasification zone 204’. As indicated in the figure, the oxidation zone 620’ may partly overlap either the pyrolysis zone 202’ and/or the gasification zone 204’. This embodiment is particularly energy efficient, since the heat from the pyrolysis in the pyrolysis zone 202’ is efficiently transferred to the oxidation zone 620’ and the gasification zone 204’, and even further to the hydrotreatment reactor

402 as indicated by arrow 411.

Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or

"comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.