Continuous oil production process by hydrothermal liquefaction

Abstract

TITLE: Process for continuous oil production by hydrothermal liquefaction. The invention relates to a process for continuous oil production by hydrothermal liquefaction, said process being carried out in a reactor containing an aqueous medium and comprising the following steps: heating the aqueous medium of the reactor to a pressure between 130 and 200 bar and a temperature between 300 and 350°C; injecting non-woody organic matter into the aqueous medium of the reactor, said organic matter comprising at least 24% lipids, the implementation of steps a) and b) resulting in the production of oil free of biochar or containing only trace amounts of biochar, such that no oil-biochar separation step is performed. Figure 1

Description

Title of the invention: Continuous oil production process by hydrothermal liquefaction. Technical field of the invention

[0001] The invention relates to the continuous production of oil by hydrothermal liquefaction.

[0002] The oil can then be used for energy purposes as a biofuel after refining for aviation, maritime transport or other. Technical background

[0003] Processes for manufacturing oil by hydrothermal liquefaction of organic matter (biomass) are known. Generally, liquefaction takes place in water, at high pressure (-170 bar) and at a temperature between 250 and 400°C. These conditions define a subcritical environment (water). In practice, the aqueous environment is located in a reactor which is heated and pressurized, and then the biomass to be treated is injected. The biomass is converted into a mixture containing oil (bio-oil), biochar (solid), gas, and various soluble molecules in the aqueous phase. After cooling and expansion of this mixture, different products are recovered, which must be separated. Cold separation between the oil and the biochar is carried out by extracting the oil with a solvent, primarily for batch (not continuous) processes, although this could also be implemented for continuous processes.

[0004] This cold separation, with a solvent, is costly in terms of time and energy, so the manufacturing processes implementing it are not economically viable on an industrial scale.

[0005] This is why hot separation processes between bio-oil and biochar have been proposed, which consist of filtering the biochar inline. See, for example, Cheng, F., T. Le Doux, et al. (2019): "Modification of a pilot-scale continuous flow reactor for hydrothermal liquefaction of wet biomass", Methods X vol. 6: pp. 2793-2806. See also Douglas C. Elliott, TRH, Andrew J. Smidt, Gary G. Neuschwander, Leslie J. Rotness, Mariefel V. Olarte, Alan H. Zacher, Karl O. Albrecht, Richard T. Hallen, Johnathan E. Holladay (2013): "Process development for hydrothermal liquefaction of algae feedstocks in a continuous-flow reactor", Algal Research vol. 2(4): pp. 445-454. However, these inline filtration solutions are difficult to develop and can lead to clogging and risks of pressure build-up in the installation.Other proposed systems rely on the use of hydraulic oscillations which help to retain the particles. solids in suspensions (Anastasakis, K., Biller, P., Madsen, RB, Glasius, M., and Johannsen, I. (2018). “Continuons Hydrothermal Liquefaction of Biomass in a Novel Pilot Plant with Heat Recovery and Hydraulic Oscillation.” Energies, 11(10).

[0006] It has also been proposed to limit biochar formation to eliminate the need for a separation step, which is particularly advantageous for continuous hydrothermal liquefaction processes. To this end, various solutions have been proposed, such as recycling the aqueous phase, using supercritical water conversion conditions (e.g., the Hydrofaction® process proposed by Steeper Energy), or adding alkali salts to the aqueous medium in which hydrothermal liquefaction is carried out. However, recycling the aqueous phase does not completely eliminate char formation, and using supercritical conditions is energy-intensive, as the heat required for the system is greater.

[0007] One objective of the invention is to offer an improved solution.

[0008] In particular, an objective of the invention is to provide an improved solution that does not require char filtration or the use of solvent while limiting the energy impact of the solution. Summary of the invention

[0009] To achieve the aforementioned objective, the invention proposes a continuous oil production process by hydrothermal liquefaction, said process being implemented in a reactor equipped with an aqueous medium and comprising the following steps: a) to set the aqueous medium of the reactor at a pressure between 130 and 220 bar, in particular between 130 and 200 bar, and a temperature between 300 and 370°C, in particular between 300 and 350°C; b) injecting a solution of non-woody organic matter into the aqueous medium of the reactor, said organic matter comprising at least 24% lipids, the implementation of steps a) and b) involving the production of oil free from biochar or containing biochar only in trace amounts so that no oil-biochar separation step is carried out.

[0010] The invention, by choosing a specific source of biomass, in this case containing a minimum level of lipids, thus limits the production of biochar or at worst to trace amounts so that no separation is necessary between the oil and the biochar.

[0011] The process according to the invention may include at least one of the following additional steps, taken alone or in combination: - the non-woody organic matter injected into the aqueous medium in step b) contains at most 60% lipids; - the non-woody organic matter injected into the aqueous environment in step b) contains at most 30% sugars, preferably between 15% and 30% sugars; - the non-woody organic matter injected into the aqueous medium in step b) comprises at most 21% protein, preferably between 12% and 21% protein; - the non-woody organic matter injected into the aqueous environment in step b) is chosen from: algae, walnut cakes, sewage sludge or a mixture of these; - the non-woody organic matter injected into the aqueous environment in step b) is made up of micro-algae. Brief description of the figures

[0012] Other objects and features of the invention will become clearer in the following description, made with reference to the accompanying figures in which:

[0013] Fig. 1 is a diagram representing the essential steps of the process that is the subject of the invention;

[0014] Fig. 2 is a diagram representing a test installation suitable for implementing the process according to the invention. Detailed description of the invention

[0015] In general, the invention relates to a continuous oil production process by hydrothermal liquefaction. The process is carried out in a reactor containing an aqueous medium and comprises the following steps: a) to maintain the aqueous environment of the reactor at a pressure between 130 and 220 bar, in particular between 130 and 200 bar, and a temperature between 300 and 370°C; in particular between 300 and 350°C, b) injecting a solution of non-woody organic matter into the aqueous medium of the reactor, said non-woody organic matter comprising at least 24% lipids, the implementation of steps a) and b) involving the production of oil free from biochar or containing biochar only in trace amounts so that no oil-biochar separation step is carried out.

[0016] By traces of biochar, it should be understood that the mass proportion of biochar in the oil recovered at the outlet of the reactor is less than or equal to 3% of the mass of dry oil, advantageously less than or equal to 1% of the mass of dry oil, even more advantageously less than or equal to 0.5% of the mass of dry oil.

[0017] It should be noted that, given the pressures and temperatures imposed during step a), hydrothermal liquefaction takes place under subcritical conditions. With the choice specific to organic matter (biomass) which is carried out, it is noted in fact that there is no particular interest in operating in supercritical mode.

[0018] One advantage of the process according to the invention is therefore to eliminate a separation step between the oil and the biochar (hot filtration in the reactor or cold solvent extraction of the oil). This makes it possible to obtain an oil that can be directly treated by hydrodeoxygenation (better known by the acronym HDO for HydroDeOxygenation in Anglo-Saxon terminology) and hydrodeazotation (better known by the acronym HDN for HydroDeNitrogenation in Anglo-Saxon terminology) in order to obtain a biofuel.

[0019] Furthermore, the mass yield of oil production is improved due to the reduction in carbon losses in solid form (biochar) and the difficulties in recovering it from the reactor piping. This also limits the clogging phenomena already observed with the processing of lignin-rich biomass and therefore facilitates long-term continuous testing.

[0020] The non-woody organic matter injected into the aqueous medium in step b) may contain up to 60% lipids. Furthermore, the non-woody organic matter injected into the aqueous medium in step b) may contain up to 30% sugars, in particular between 15% and 30% sugars. Finally, the non-woody organic matter injected into the aqueous medium in step b) may contain up to 21% lipids, in particular between 12% and 21% proteins. The non-woody organic matter injected into the aqueous medium in step b) may form an aqueous mixture containing between 10% and 20% by mass of organic matter in the water.

[0021] In particular, the non-woody organic matter injected into the aqueous medium in step b) may be chosen from: algae, nut cakes, sewage sludge or a mixture of these.

[0022] In particular, microalgae may be chosen. Such algae constitute a particularly interesting resource because of their high growth rate and make it easier to form a solution that can be injected into the aqueous environment of the reactor.

[0023] Fig. 2 is a simplified diagram of an experimental installation suitable for implementing the process according to the invention and with which various tests were conducted.

[0024] The solution used is a microalgae-based solution containing 10% organic matter (algal solution). The algal solution is introduced into a tank CUV1 which is constantly agitated by a rotary mixer MR driven by a motor ML. The rotary mixer MR ensures that the microalgae are distributed homogeneously within the solution.

[0025] Reactor R is preheated by resistive collars (not shown) to a set temperature. During this phase, a water circulation from a Another tank, CUV2, is constructed to raise the reactor temperature. This limits the temperature ramp experienced by the algal solution when it is introduced into reactor R.

[0026] A first pump PI regulates the flow rate of the algal solution and a second pump P2 regulates the pressure in the installation.

[0027] When the set temperature of reactor R is reached, the algal solution is fed from the first tank CUV1, for example at a flow rate of 1.5 L / h. Reactor R (which operates continuously) is also agitated by a shaft ARB powered by a motor M, the shaft being fitted with blades PL distributed along the length of reactor R. The reaction typically lasts between 10 and 15 minutes.

[0028] At the outlet of reactor R, the products from hydrothermal liquefaction (bio-oil and aqueous phase) are cooled by an ECH heat exchanger whose secondary fluid is regulated at 40 °C (secondary circuit not shown). The products from hydrothermal liquefaction (bio-oil and aqueous phase) are sent by pumps PI, P2 from the outlet of reactor R to the CUV3 tank during the conversion phase (under steady-state conditions). During operation of the installation, the temperature is measured at various points of reactor R at the reactor outlet, as well as upstream and downstream of the ECH heat exchanger, to ensure the proper functioning of the heating collars and the cooling supply (not shown in [Fig. 2]) enabling the ECH heat exchanger to cool the products.

[0029] During the transition phases (stop and start), the outgoing flow from reactor R is sent by pumps P3, P4 to a buffer tank CUV4.

[0030] Three tests were carried out under the aforementioned conditions.

[0031] A first test (RAF47) was carried out at a temperature of 300°C and a pressure of 130 bar with an algal solution (microalgae) having the following composition: 36.8% lipids, 29.2% sugars and 11.8% proteins. This resulted in a bio-oil mass yield of 45.2% and the production of 0.2% biochar by mass.

[0032] A second test (RAF55) was carried out at a temperature of 340°C and a pressure of 190 bar with an algal (microalgae) solution having the following composition: 37.3% lipids, 33.4% sugars, and 12.5% ​​proteins. This resulted in a bio-oil mass yield of 47.7%, the bio-oil being free of biochar (no trace of biochar).

[0033] Finally, a third test (RAF57) was carried out at a temperature of 340°C and a pressure of 190 bar with an algal (microalgae) solution having the following composition: 24.5% lipids, 30.3% sugars, and 18.2% proteins. This resulted in a bio-oil mass yield of 47.4%, the bio-oil being free of biochar (no trace of biochar).

[0034] In all of these tests, no separation step of the products of my hydrothermal liquefaction (Bio-oil / possible biochar) was carried out.

[0035] As can be seen by comparing the tests, increasing the temperature has the effect of reducing the percentage of biochar and even eliminating it.

[0036] Furthermore, it is also possible to improve the mass yield of bio-oil by adjusting certain parameters. For example, the proportion of non-woody organic matter in the solution (algal or other) intended for injection into the reactor can be increased. Alternatively, the reaction time can also be reduced. Finally, recycling the aqueous phase could also be considered, at least partially, if the initial non-woody organic matter (biomass) is supplied with a water content of less than 90%.

[0037] Furthermore, the use of specific organic matter can be envisaged. For example, a C. vulgaris strain is more suitable than a C. sorokiniana strain with regard to the nitrogen content in the bio-oil. The nitrogen content in the bio-oil is an important parameter to consider in order to improve the quality of the bio-oil for its application as a biofuel.

Claims

Demands

1. A process for the continuous production of oil by hydrothermal liquefaction, said process being carried out in a reactor equipped with an aqueous medium and comprising the following steps: a. bringing the aqueous medium of the reactor to a pressure of between 130 and 220 bar, in particular between 130 and 200 bar, and a temperature of between 300 and 370°C, in particular between 300 and 350°C; b. injecting a solution of non-woody organic matter into the aqueous medium of the reactor, said organic matter comprising at least 24% lipids, the implementation of steps a) and b) involving the production of oil free from biochar or containing biochar only in trace amounts such that no oil-biochar separation step is carried out.

2. A continuous manufacturing process by hydrothermal liquefaction according to claim 1, wherein the non-woody organic material injected into the aqueous medium in step b) comprises at most 60% lipids.

3. A continuous manufacturing process by hydrothermal liquefaction according to the preceding claim, wherein the non-woody organic matter injected into the aqueous medium in step b) comprises at most 30% sugars, preferably between 15% and 30% sugars.

4. A continuous manufacturing process by hydrothermal liquefaction according to any one of claims 2 or 3, wherein the non-woody organic matter injected into the aqueous medium in step b) comprises at most 21% protein, preferably between 12% and 21% protein.

5. A continuous manufacturing process by hydrothermal liquefaction according to any one of the preceding claims, wherein the non-woody organic matter injected into the aqueous medium in step b) is selected from: algae, nut cakes, sewage sludge or a mixture thereof.

6. A continuous manufacturing process by hydrothermal liquefaction according to the preceding claim, wherein the organic matter non-woody material injected into the aqueous medium in step b) is formed of micro-algae.

Images