Cooler for product(s) originating from a thermochemical reactor, and hydrothermal liquefaction or carbonization plant incorporating such a cooler

Abstract

The invention relates to a cooling device (6) for product(s) originating from a reactor (4) for hydrothermal liquefaction or carbonization of a biomass, comprising: - a casing (60) forming a shell comprising an injection opening; - a first duct (61) in which a cooling liquid circulates, the first duct being connected to the injection opening in order to inject a stream of the cooling liquid into the shell; - a second duct (62) in which a stream of product(s) originating from the reactor circulates, the second duct passing through the shell and comprising a portion which is provided with at least one hole that opens into the shell in order to inject the stream of cooling liquid into the stream of product(s) originating from the reactor, such that the latter is at a lower temperature but at a higher speed downstream than upstream of the portion.

Description

[0001] Description

[0002] Title: Cooler for product(s) from a thermochemical reactor, Hydrothermal liquefaction or carbonization installation incorporating such a cooler.

[0003] Technical field

[0004] The present invention relates to the field of hydrothermal liquefaction or carbonization.

[0005] The invention essentially aims to provide effective cooling which eliminates, or at least significantly reduces, clogging at the outlet of the hydrothermal liquefaction or carbonization reactor.

[0006] Although described with reference to hydrothermal liquefaction, the invention applies to any thermochemical application requiring the cooling of a product from an upstream reactor which is likely to clog a surface of an evacuation conduit by deposit.

[0007] Prior art

[0008] Hydrothermal liquefaction is a thermochemical depolymerization process used to convert wet biomass and other macromolecules into crude oil at moderate temperature typically 280-350°C and pressure above saturation pressure, typically 120-200 bar: [1].

[0009] A typical installation using hydrothermal liquefaction is illustrated in Figure 1.

[0010] Plant 1 comprises a unit 2 for preparing the biomass mixture to be converted (slurry) which is fed by a pump 3 to a downstream reactor 4 in which the thermochemical reaction takes place.

[0011] Downstream of reactor 4, a unit 5 separates the products obtained by hydrothermal liquefaction. The separation of these products can be implemented either by gravity difference for separation by decantation, or by particle size for separation on a sieve. As illustrated in this figure 1, the purged water from unit 2 can be injected to carry out the separation.

[0012] In reactor 4, the organic matter is pressurized and heated typically to 300°C. The pressure is adjusted so that the mixture remains liquid water. The pressure is thus typically between 100 and 120 bar for 300°C. For a temperature of 350°C, the pressure is rather between 200 and 220 bar.

[0013] Yields within such a reactor vary greatly, depending on the resources. The main product is called biocrude: it consists of a heavy oil with varying amounts of solids, called char. About 40 to 60% of the dry mass of the introduced biomass is converted into biocrude. About 10% of this dry mass is converted into CO2.

[0014] The liquefaction process also produces an aqueous phase rich in organic molecules, such as carboxylic acids, phenolics, alcohols, and many others. These molecules remain in the aqueous phase thanks to a high oxygenation rate. Approximately 30 to 50% of the dry mass of the introduced biomass is retained in the aqueous phase.

[0015] Hydrothermal carbonization is a very similar process, but takes place at lower temperatures, typically 200 to 250 °C, with slightly longer reaction times, typically around one hour. About 50 to 70% of the dry matter of the introduced biomass is converted into a solid. The product, called hydrochar, is typically used as fuel or to upgrade other materials.

[0016] Whether for liquefaction or hydrothermal carbonization, the resulting biocrude or hydrochar flow must be cooled significantly downstream, particularly to a temperature compatible with separation.

[0017] To do this, it is known to implement shell and tube heat exchangers in hydrothermal liquefaction installations.

[0018] The major disadvantage of shell and tube exchangers is that they tend to clog. While they do allow cooling of the flow from the reactor, when the cooling is too great, and therefore the flow temperature is too low, the biocrude tends to stick to the tube walls, thereby limiting heat exchange and therefore the exchanger performance.

[0019] In the field of hydrothermal gasification, it is known to cool a gaseous flow obtained by gasification by mixing it with a cold flow. We can refer to the gasification system described in article [2] or the entrained flow system marketed under the name PRENFLO or described in article [3]. In the system of article [2], the gas produced by the gasifier is too hot to be cooled directly in an exchanger. A circulator recovers a significant part of the cooled flow to inject it into the hot gaseous flow to lower its temperature. The gas flow produced is cooled in an exchanger and can be manipulated subsequently. In the quantitative example indicated in [2], the gas is produced in the gasifier at 1500 °C, gas at 200 °C is injected into the top of the gasifier to reach 600 °C. The mixed flow is thus cooled from 600 °C to 200 °C.

[0020] A device for increasing the speed of a flow of produced material has been implemented in a pilot hydrothermal liquefaction installation: [4]. Figure 1 of this publication [4] shows a diagram of the pilot installation which includes a biomass preparation unit equipped with a pump to feed a downstream reactor essentially in the form of a very long tube, equal to 140 m for an internal diameter of 14.2 mm. The inlet portion of the tube is heated by exchange with the flow leaving the reactor to recover a maximum of heat. The major part of the reactor is heated by electrical tracing.

[0021] A cooler is arranged at the reactor outlet with a fluidic oscillator arranged on either side of it.

[0022] These two fluidic oscillators create a back and forth movement inside the reactor, the function of which is to prevent accumulations of material.

[0023] The disadvantage of these oscillators is that, at times, they push against the main flow produced in the reactor, which increases the inlet pressure and hinders the operation of the pumps and sometimes they suck the flow, which, conversely, significantly lowers the pressure with a risk that it has a value below the saturation pressure, a value which does not allow the hydrothermal liquefaction reaction to take place. Because of this disadvantage, the amplitude of the oscillators must be limited and therefore their efficiency is much lower than that sought.

[0024] There is therefore a need to find an effective solution to avoid clogging by deposit of material of at least some of the components of a hydrothermal liquefaction or carbonization installation, by overcoming the aforementioned drawbacks.

[0025] The aim of the invention is to meet at least part of this need. Description of the invention

[0026] To this end, the invention relates, in one of its aspects, to a device for cooling product(s) from a reactor for the liquefaction or hydrothermal carbonization of biomass, comprising:

[0027] - an envelope forming a grille comprising an injection opening;

[0028] - a first conduit in which a coolant circulates, the first conduit being connected to the injection opening to inject a flow of coolant into the grille;

[0029] - a second conduit in which a flow of product(s) from the reactor circulates, the second conduit passing through the shell and comprising a portion which is provided with at least one hole opening into the shell to inject the flow of coolant into the flow of product(s) from the reactor so that the latter is at a lower temperature but at a higher speed downstream than upstream of the portion.

[0030] Preferably, the device comprises a plurality of through holes preferably distributed regularly along the portion of the second conduit.

[0031] According to a first alternative, each hole is formed by drilling through the wall of the second conduit.

[0032] According to a second alternative, each hole is formed by the interior of a nozzle fixed or made entirely through the wall of the second conduit.

[0033] Advantageously, the speed of the flow of coolant in the first conduit and the shell is adapted so that the ratio between the speed of the flow of product(s) from the reactor downstream of the portion with hole(s) and that upstream is at least equal to 10, preferably at least equal to 25, more preferably between 25 and 50.

[0034] The invention also relates to a plant for the hydrothermal liquefaction or carbonization of biomass, comprising:

[0035] - a hydrothermal liquefaction or carbonization reactor;

[0036] - a cooling device as described above, the second conduit of which is connected upstream to the reactor; - a cyclonic separator the inlet of which is connected upstream to the second conduit of the device so as to separate the flow of product(s),

[0037] - an injection pump arranged on the first conduit so as to inject a flow of aqueous phase into the calender, as a coolant.

[0038] Thus, in such a plant, a rich flow with the product of liquefaction or carbonization exits from the bottom, the clean liquid exits from the top and is separated. Part of the flow that is separated and exits the cyclone returns to the reactor inlet. The other part of the flow exiting the cyclone separator, without particles, is separated into a flow, used for cooling and reinjected into the shell of the cooling device. The other part is used for the preparation of biomass.

[0039] According to an advantageous embodiment, the installation comprises a decantation or granulometry separation unit, connected upstream to one of the two outlets of the cyclonic separator to separate the flow of product(s) concentrated by the latter from the aqueous phase.

[0040] According to another advantageous embodiment, the installation comprises at least one heat exchanger arranged on the first conduit so as to cool the aqueous phase flow extracted from the outlet of the cyclone, before its injection into the calender. The heat exchanger may be of the tube and calender type with water circulation within it, or an air heater whose operation is ensured by electrical power supply, or other.

[0041] According to an advantageous embodiment variant, the other of the two outlets of the cyclone separator is connected to the first conduit of the device to inject a flow of aqueous phase of the flow of product(s) extracted from the outlet of the cyclone into the calender.

[0042] According to another advantageous embodiment, the installation comprises:

[0043] - a biomass preparation unit upstream of the reactor;

[0044] - a third conduit connected upstream to the preparation unit and connected downstream to the first conduit to inject into the calender a flow of aqueous phase coming from the preparation unit.

[0045] According to another advantageous embodiment, the other of the two outlets of the separator is connected to the junction between the first conduit and the third conduit to inject into the calender both the aqueous phase flow coming from the preparation unit and that extracted from the cyclonic separator. When the installation implements hydrothermal liquefaction, the product from the reactor is biocrude suspended in an aqueous phase.

[0046] Preferably, the proportion of biocrude is between 10 and 20% for a proportion of aqueous phase between 80 and 90%.

[0047] Thus, the invention essentially consists of a cooler for a flow of product(s) from a hydrothermal liquefaction or carbonization reactor which circulates in a perforated tube at the level of an injection shell of a coolant whose flow injected through the perforation(s) will mix with the flow of product(s). The flow rate and speed of the resulting flow, downstream of the perforations is greatly increased compared to the flow upstream of the perforations. This increased speed of the resulting flow prevents the deposition of the product(s), in particular the biocrude from the hydrothermal liquefaction, on the walls of the pipes of the installation, downstream. The increase in speed is typically in a ratio of 25 to 50 compared to the speed of the flow upstream of the perforations.

[0048] In the hydrothermal liquefaction or hydrothermal carbonization installation, the coolant flow advantageously comes from the aqueous phase extracted and injected by a pump from a cyclonic separator which recovers the resulting accelerated flow, the extracted product(s) being concentrated by the cyclonic separator then separated downstream by decantation or granulometry through a sieve.

[0049] Other advantages and characteristics of the invention will become more apparent upon reading the detailed description of examples of implementation of the invention given by way of illustration and not limitation with reference to the following figures.

[0050] Brief description of the drawings

[0051] [Fig 1] Figure 1 is a schematic representation of a hydrothermal liquefaction plant with state-of-the-art material flows.

[0052] [Fig 2A], [Fig 2B] Figures 2A, 2B are schematic views of a device for cooling a flow of product(s) from a liquefaction or hydrothermal carbonization reactor according to respectively a first alternative and a second alternative embodiment of the invention.

[0053] [Fig 3] Figure 3 is a schematic view of a downstream part of a hydrothermal liquefaction or carbonization installation integrating a cooling device according to the invention. [Fig 4] Figure 4 is a schematic representation of a hydrothermal liquefaction installation with the material flows according to the invention.

[0054] Detailed description

[0055] Throughout the application, the terms "upstream", "downstream", "inlet", "outlet" are to be considered in relation to the direction of circulation of a flow in a cooler and hydrothermal liquefaction or hydrothermal carbonization installation according to the invention.

[0056] For the sake of clarity, the same element according to the state of the art and according to the invention is designated by the same numerical reference.

[0057] Figure 1 has already been commented on in the preamble. It will therefore not be detailed below.

[0058] Figures 2A, 2B show two alternatives of a cooling and recovery device according to the invention for a flow Ml of biocrude suspended in an aqueous phase, as it is discharged from a hydrothermal liquefaction reactor 4. Typically, at the outlet of a reactor 4, the flow Ml consists of an aqueous phase, in a proportion of 80 to 90%, and the biocrude in suspension, in a proportion of 10 to 20%.

[0059] The device 6 firstly comprises an envelope 60 forming a calender comprising an injection opening.

[0060] A first conduit 61 in which a coolant circulates is connected to the intake opening to inject a flow M7 of the coolant into the grille 60.

[0061] A second conduit 62 in which the flow Ml circulates crosses the calender 60, comprises a portion E1 which is provided with a plurality of holes 63 or 64 opening into the calender 60.

[0062] These holes 63 or 64 are preferably distributed by being regularly spaced along the portion El. These holes 63 or 64 therefore make it possible to inject the flow M7 of coolant into the flow Ml coming from the hydrothermal liquefaction reactor upstream so that the latter is at a lower temperature but at a higher speed downstream than upstream of the portion.

[0063] In other words, the resulting flow M2 of suspended biocrude has an increased flow rate and speed compared to those of the upstream flow M1. This increased speed in the conduit 62 of the flow M2 makes it possible to avoid the deposition of biocrude particles on the wall of the conduit 62, and therefore to avoid fouling it and thereby to avoid premature shutdown for cleaning of the hydrothermal liquefaction installation.

[0064] Advantageously, the speed ratio between that of the flow M2 and that of the flow M1 upstream of the calender 60 is greater than 10, preferably greater than 25, in particular between 25 and 50.

[0065] For ease of manufacture, the section of the second duct 62 can be constant over its entire length, i.e. upstream, inside and downstream of the calender 60. It is also possible to reduce the section of the duct 62 in its portion downstream of the perforated portion El so as to obtain an even greater speed for the flow M2.

[0066] Each hole may consist of a bore 63 directly through the wall of the conduit 62 (Figure 2A), or be delimited by the interior of a nozzle 64 fixed or made entirely through the wall of the conduit 62 (Figure 2B).

[0067] Figure 3 shows an advantageous embodiment according to which the cooling liquid injected as flow M7 is a flow of aqueous phase recovered from a cyclonic separator 7 whose inlet 70 is connected upstream to the conduit 62 of the device 6.

[0068] Cooling and increasing the velocity of the M2 stream dilutes the biocrude into more aqueous phase. The cyclone separator 7 does not completely separate the aqueous phase from the biocrude but produces an M3 stream that concentrates the biocrude.

[0069] An injection pump 8 arranged on the conduit 61 makes it possible to inject the aqueous phase flow M7 into the calender 60.

[0070] Thus in this mode, the outlet 71 of the cyclonic separator is connected to the conduit 61 of the device 6 to inject a flow M5 of aqueous phase extracted from the outlet 71 of the cyclone, which is previously cooled M6 by means of a heat exchanger 9 at E2 in the shell 60. This exchanger 9 can be of the liquid / liquid exchanger type, in particular with water or an air heater, preferably operating by electrical power supply.

[0071] A unit 5 for separation by decantation or granulometry using a sieve 50 is connected upstream to the outlet 72 of the cyclonic separator 7 to separate the flow M3 of biocrude concentrated by the latter from the aqueous phase M5. The section of the conduit 61 can be narrowed relative to the outlet 71 of the cyclonic separator 7 in order to accelerate the flow M5, M6, M7 of aqueous phase. The cyclonic separator 7 is adapted so that the speed of the aqueous phase in the conduit 61 is advantageously between 5 and 10 cm / s as suggested by [4].

[0072] The temperatures and pressures are given for illustrative purposes for the operation of a hydrothermal liquefaction plant for a standard biomass.

[0073] As illustrated in Figures 3 and 4, a third conduit 65 connected upstream to the preparation unit 2 of the installation can be connected downstream to the conduit 61 to inject into the calender a flow M4 of aqueous phase coming from the preparation unit 2.

[0074] More precisely, preferably the outlet 71 of the cyclonic separator 7 is connected to the junction between the conduits 61 and 65 to inject into the calender 60 both the flow M4 of aqueous phase coming from the preparation unit and that extracted from the separator 7.

[0075] Figure 4 illustrates the synoptic of a hydrothermal liquefaction installation 1 according to the invention where we see that compared to a currently existing installation, as illustrated in Figure 1, only the downstream part, between the reactor 4 and the separation unit 5 is modified. It is thus easy to retrofit an existing installation 1.

[0076] The inventor carried out simulations of the dimensioning of the different flows and powers required for the operation of the downstream part of a hydrothermal liquefaction installation as according to the invention.

[0077] Table 1 below gives dimensional values ​​for an experimental installation of the applicant with a flow rate of 1 kg / h or 0.1 kg / h of dry matter. [Table 1]

[0078] Table 2 below gives sized values ​​for an industrial installation with a flow rate of 10t / h or It / h of dry matter. [Table 2]

[0079] The invention is not limited to the examples which have just been described; in particular, it is possible to combine characteristics of the examples illustrated within non-illustrated variants.

[0080] Other variations and improvements may be envisaged without departing from the scope of the invention.

[0081] In the example of the configuration of Figures 3 and 4, the biocrude produced is that of most biomass resources, such as digestate, food waste, algae, etc. and therefore is lighter than water. Thus, such a biocrude lighter than water, the cyclone separator 7 has its outlet 71 from above through which the aqueous phase is extracted and its outlet 72 from below through which the M3 stream of concentrated biocrude is discharged.

[0082] However, some biomass resources produce a biocrude heavier than water, such as black liquor or woody biomass. In this case, the outlets of the cyclone separator 7 are reversed compared to the configuration of Figures 3 and 4, i.e. the outlet 71 on top is arranged to extract the biocrude while the outlet 72 on the bottom extracts the aqueous phase.

[0083] Furthermore, depending on the intended applications, it is preferable to add bypass ducts from the recirculation pump 8 to the cyclone separator 7 so as to bypass the cooling in the case where the optimal speed in the separator 7 is higher than the optimal speed for cooling M7. In other words, the outlet 61 of the pump P is connected, through a control valve, to the duct 70 of the cyclone. A bypass duct of the cyclone separator can be envisaged in the case where the flow rate in the cyclone is too high, therefore from the duct 70 to 72, through a control valve. List of cited references

[0084] [1]: G. Haarlemmer, M. Briand, A. Roubaud, J. Roussely, M. Déniel, “Economie evaluation of a hydrothermal liquefaction process". Detritus, 3 (2018) 84-92. https: / / doi.org / 10.31025 / 2611-4135 / 2018.13695. [2]: H J. van der Ploeg, T. Chhoa, P.L. Zuideveld, “77ze Shell Coal Gasification Process for the US Industry". Washington DC, USA, 2004,

[0085] [3]: K. Radtke, M. Heinritz- Adrian, M. Hooper, B. Richards, “Prenflo: PSG and PDQ,” Washington 2008.

[0086] [4]: K. Anastasakis, P. Biller, R.B. Madsen, M. Glasius, I. Johannsen, “Continuous Hydrothermal Liquefaction of Biomass in a Novel Pilot Plant with Heat Recovery and

[0087] Hydraulic Oscillation" , Energies, 11 (2018) 269

Claims

Claims 1. Cooling device (6) for product(s) from a reactor (4) for the liquefaction or hydrothermal carbonization of biomass, comprising: - an envelope (60) forming a calender comprising an injection opening; - a first conduit (61) in which a coolant circulates, the first conduit being connected to the injection opening to inject a flow of coolant into the grille; - a second conduit (62) in which a flow of product(s) from the reactor circulates, the second conduit passing through the shell and comprising a portion which is provided with at least one hole opening into the shell to inject the flow of coolant into the flow of product(s) from the reactor so that the latter is at a lower temperature but at a higher speed downstream than upstream of the portion.

2. Device (6) according to claim 1, comprising a plurality of through holes preferably distributed regularly spaced along the portion of the second conduit.

3. Device (6) according to one of claims 1 or 2, each hole being constituted by a drilling (63) through the wall of the second conduit.

4. Device (6) according to one of claims 1 or 2, each hole being constituted by the interior of a nozzle (64) fixed or made entirely through the wall of the second conduit.

5. Device (6) according to one of the preceding claims, the speed of the flow of cooling liquid in the first conduit and the shell being adapted so that the ratio between the speed of the flow of product(s) from the reactor downstream of the portion with hole(s) and that upstream is at least equal to 10, preferably at least equal to 25, more preferably between 25 and 50.

6. Installation (1) for hydrothermal liquefaction or carbonization of biomass, comprising: - a hydrothermal liquefaction or carbonization reactor (4); - a cooling device (6) according to one of the preceding claims, the second conduit (62) of which is connected upstream to the reactor; - a cyclonic separator (7) whose inlet is connected upstream to the second conduit of the device so as to separate the flow of product(s); - an injection pump (8) arranged on the first conduit so as to inject into the calender a flow of aqueous phase, as coolant.

7. Installation (1) according to claim 6, comprising a unit (5) for separation by decantation or granulometry, connected upstream to one of the two outlets of the cyclonic separator to separate the flow of product(s) concentrated by the latter from the aqueous phase.

8. Installation (1) according to claim 6 or 7, one of the outlets of the cyclonic separator being connected to the first conduit of the device for injecting a flow of aqueous phase of the flow of product(s) extracted from the outlet of the cyclone into the calender.

9. Installation (1) according to the preceding claim, comprising at least one heat exchanger (9) arranged on the first conduit so as to cool the flow of aqueous phase extracted from the outlet of the cyclone, before its injection into the calender.

10. Installation according to one of claims 6 to 9, comprising: - a unit (2) for preparing the biomass upstream of the reactor; - a third conduit (65) connected upstream to the preparation unit and connected downstream to the first conduit to inject into the calender a flow of aqueous phase coming from the preparation unit.

11. Installation (1) according to claim 10 and 11, the other of the two outlets of the separator being connected to the junction between the first conduit and the third conduit to inject into the calender both the aqueous phase flow coming from the preparation unit and that extracted from the cyclonic separator.

12. Hydrothermal liquefaction installation (1) according to one of claims 6 to 11, configured so that the product from the reactor is biocrude suspended in an aqueous phase.

13. Installation (1) according to claim 12, the proportion of biocrude being between 10 and 20% for a proportion of aqueous phase between 80 and 90%.

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