DE102010062833B3 - Hydrothermal carbonization of biomass in a deep shaft reactor, comprises providing flowable starting mixture, supplying the starting mixture and maintaining the downstream reducing conditions - Google Patents

Abstract

Hydrothermal carbonization of biomass in a deep shaft reactor comprises: providing a flowable starting mixture, which comprises biomass suspended in water and optionally comprising at least one catalysts (3); supplying the starting mixture to a deep shaft reactor; and maintaining the downstream reducing conditions, in which the hydrothermal carbonization of the starting mixture in the descending allows biomass to form particulate carbon-rich compounds, where upstream resultant reaction mixture is added with oxygen-containing fluid. Hydrothermal carbonization of biomass in a deep shaft reactor comprises: providing a flowable starting mixture, which comprises biomass suspended in water and optionally comprising at least one catalysts (3); supplying the starting mixture to a deep shaft reactor; and maintaining the downstream reducing conditions, in which the hydrothermal carbonization of the starting mixture in the descending allows biomass to form particulate carbon-rich compounds, where upstream resultant reaction mixture is added with oxygen-containing fluid, such that dissolved organic compounds in ascending reaction mixture are implemented by wet oxidation. An independent claim is also included for a deep shaft reactor to perform a method comprising a leader in a depth of the reaction vessel for the downstream, which is down-comer, where the down-comer is designed such that the down-comer is fed with starting mixture and can be conducted in the downstream into the deep; and the reaction vessel has fluid-conducting leader connected upwards with the down comer for the upward flow, which is up-comer, where the up-comer is designed such that it can be conducted according to the down-comer in the depths of escaping reaction mixture in the up-comer transferable and the upstream, where the deep shaft reactor has a device for introducing the oxygen-containing fluid into the upstream in the up-comer.

Description

Hydrothermal carbonation (HTC) is a chemical process for the simple and high-efficiency production of particulate, carbon-rich substances such. B. lignite substitutes or humus from biomass with release of energy. The reaction product of HTC can be referred to simply as 'biochar'. In WO 2008/113309 A1 describes the implementation of a hydrothermal carbonization using a deep shaft reactor.

In the HTC biomass, in particular plant material, (in the following reaction equation simplifying as a monosaccharide with the formula C ₆ H ₁₂ O ₆ described) together with water in the presence of a catalyst such. As citric acid or even without such under pressure. At this time, the pressure may increase to 2-4 MPa or higher depending on the temperature used, which is usually set between 180 ° C and 240 ° C. The ongoing reaction is exothermic. After a reaction time in the autoclave of 1 to 12 hours, the reactants - mainly by hydrolysis and condensation reactions - largely to fully implemented. The majority of the organic carbon (about 80 to 95%) is present as an aqueous suspension of particulate, carbon-rich compounds with the approximate molecular formula C ₆ H ₂ O. The remaining 5 to 20% carbon are substantially as undesirable hydrolysis products, eg. B. as short-chain organic acids and furan derivatives, dissolved in the aqueous phase before. The molecular weights of the dissolved products range from simple low molecular weight compounds to high molecular weight condensation products.

The reaction equation for the formation of biochar by HTC is approximately: C ₆ H ₁₂ O ₆ → C ₆ H ₂ O + 5H ₂ O; ΔH = -1.105 kJ / mol

The main results of the HTC are that a) the specific calorific value of the biochar can be significantly increased compared to the biomass used, b) biochar can be dewatered more easily and energetically more efficiently than the original biomass and c) biochar, unlike native biomass, is a long-lived C Substrate for soil improvement and carbon sequestration (CO ₂ binding) can be used. One hitherto unsolved problem of the small and large-scale implementation of the HTC is the treatment of HTC's high-loaded organic process water. The HTC aims at the formation of useful carbon-rich products and, where appropriate, the destruction of pollutants adhering to the starting material. The simultaneous formation of dissolved in the process water, by filtration not separable organic compounds is undesirable, but unavoidable for chemical reasons when using the above reaction conditions. Thus, the process waters of the HTC are heavily contaminated by unwanted hydrolysis and must be cleaned consuming, before the water can be fed to another use or knocked off in the receiving water. In addition, the organic carbon contained in the process water is lost for further use within the meaning of the HTC process. In EP 2 206 688 A1 the treatment of process waters of a hydrothermal carbonation by means of wet oxidation is described.

The object of the present invention is to avoid or reduce one or more disadvantages of the prior art. In particular, it is an object of the invention to provide means and ways that allow efficient process management and lead to less polluted reaction waters.

• – ein fließfähiges Ausgangsgemisch bereitgestellt wird, welches in Wasser suspendierte Biomasse und ggf. einen oder mehrere Katalysatoren umfasst oder daraus besteht;
• – das Ausgangsgemisch einem Tiefschacht-Reaktor zugeführt wird;
• – im Abwärtsstrom des Reaktors reduzierende Bedingungen eingehalten werden, die die Karbonisierung der im absteigenden Ausgangsgemisch enthaltenen Biomasse zu partikulären, kohlenstoffreichen Verbindungen erlauben; und
• – im Aufwärtsstrom dem erhaltenen Reaktionsgemisch sauerstoffhaltiges Fluid zugesetzt wird, so dass im aufsteigenden Reaktionsgemisch gelöste organische Verbindungen durch Nassoxidation umsetzbar sind.

The object is achieved by providing a process for the hydrothermal carbonization (HTC) of biomass in a deep shaft reactor, characterized in that:

• Providing a flowable starting mixture comprising or consisting of biomass suspended in water and optionally one or more catalysts;
• - The starting mixture is fed to a deep well reactor;
• - in the downstream of the reactor reducing conditions are met, which allow the carbonization of the biomass contained in the descending starting mixture to particulate, carbon-rich compounds; and
• - In the upward flow of the resulting reaction mixture oxygen-containing fluid is added, so that in the ascending reaction mixture dissolved organic compounds by wet oxidation can be implemented.

Preferably, the O ₂ -containing fluid is supplied exclusively to the upward flow, while avoiding, complicating or excluding contact of the starting mixture in the downward flow with the oxygen-containing fluid.

• – ein in die Tiefe führendes Reaktionsgefäß für den Abwärtsstrom, der sogenannte ”down-comer”, wobei der ”down-comer” derart ausgeführt ist, dass dem ”down-comer” Ausgangsgemisch zuführbar und im Abwärtsstrom in die Tiefe leitbar ist;
• – ein mit dem ”down comer” Fluid-leitend verbundenes aufwärts führendes Reaktionsgefäß für den Aufwärtsstrom, der sog. ”up-comer”, wobei der ”up-comer” derart ausgeführt ist, dass damit aus dem ”down-comer” in der Tiefe austretendes Reaktionsgemisch in den ”up-comer” überführbar und im Aufwärtsstrom nach oben leitbar ist;
• – eine Vorrichtung zur Einbringung von sauerstoffhaltigem Fluid in den Aufwärtsstrom im ”up-comer”.

The invention also relates to a deep-shaft reactor for carrying out the process according to the invention, characterized in that the deep-shaft reactor has:

• A down-flow reaction vessel, the so-called "down-comer", wherein the "down-comer" is designed such that it can be fed to the "down-comer" starting mixture and can be conducted downwards in the downward direction;
• An upflow reactor connected to the downcomer in a fluid-conducting manner, the so-called "up-comer", wherein the "up-comer" is designed in such a way that it comes from the "down-comer" in the Deep exiting reaction mixture in the "up-comer" convertible and in upward flow can be conducted upwards;
• - An apparatus for introducing oxygen-containing fluid in the upward flow in the "up comer".

The method or deep well reactor according to the invention is based on the finding that the HTC of biomasses can advantageously be carried out in a deep-shaft reactor and can thus be combined with a wet oxidation of undesired reaction products in the reaction wastewater of the HTC such that both the obtained Wastewater is contaminated with significantly less pollutants and energy synergies can be used in the process. The process in the deep shaft reactor is designed and controlled in such a way that down stream prevail, the HTC of biomass to carbon-rich, particulate compounds and allow, by targeted introduction of O ₂ in the upstream oxidizing conditions for the wet oxidation of the reaction mixture dissolved, undesirable hydrolysis products can be achieved. In this case, the additionally released during the wet oxidation in the upward flow heat can be used directly to provide the necessary temperatures for the HTC in the downward flow. The efficiency of the process according to the invention is based on the fact that the particulate, carbon-rich compounds which are formed in the HTC and suspended in the process water oxidize more slowly than the undesired organic compounds which are present in solution in the water of reaction. In the first part of the process, the desired products of the HTC are prepared in the downflow and "stabilized" against oxidation by carbonation, while the wet oxidation preferably takes place in the water of reaction dissolved undesirable hydrolysis products at a suitable point in the upward flow of the second part of the process.

The inventive method relates to a HTC of biomass in a deep well reactor. Biomass means any kind and form of organic matter. In this case, biomass includes, in particular, living and / or dead plants, as well as parts thereof and the organic substance derived therefrom, as well as animals, fungi and microorganisms.

Organic compounds contained in the biomass are converted by HTC into particulate, carbon-rich compounds. In doing so, water and heat energy are released. The process conditions for an efficient operation of the HTC are known to those skilled in the art and described in the literature. Thus, the biomass in aqueous suspension is usually reacted at elevated temperatures of for example 180 ° C to 240 ° C and a pressure of 1.5 MPa to 3.5 MPa. These process conditions can also be represented in a so-called deep well reactor. The deep well reactor is based on the recognition that certain Tempearatur- and pressure conditions can also be generated by the fact that the reaction mixture is lowered to a predetermined depth below the ground, reacts there and then returned to the surface. A specific feature of deep well reactors is that due to the hydrostatic pressure of the water column, high pressures prevail in the deeper regions of the reactor, while reactor inlet and outlet can be charged at low pressures. This significantly simplifies the process technology to be used (pumps, locks, valves, etc.).

Reactors of the deep well reactor type are already known and their basic structure is, for example, in US 4,744,909 . EP 0 282 276 A1 described. The deep well reactors described therein are optimized for carrying out wet oxidation during the downward and upward flow (see also J. Grän-Heefeld et al .: "Modeling and simulation of a deep well reactor for the wet air oxidation of sewage sludge"). , Chemical Engineering and Processing (1995), 34, 121-126, in particular in 1 ). These deep-shaft reactors can be rebuilt and modified without difficulty for carrying out the method according to the invention, in which the supply of oxygen-containing fluid is not carried out in the downward flow, but the oxygen-containing fluid is added only in an upward direction at a suitable location.

First, a flowable starting mixture is provided which comprises biomass suspended in water. The degree of comminution of the biomass and the solids content of the resulting suspension are adjusted so that a sufficiently flowable suspension is obtained. The viscosity of the suspension is chosen so that a predetermined flow rate is achieved in the deep well reactor at a given overpressure. The starting mixture may contain one or more catalysts, for example one organic or inorganic acid, one or more metals and / or salts thereof.

The starting mixture is fed to the deep well reactor. For this purpose, the starting mixture can be fed into the deep well reactor with a predetermined overpressure. The starting mixture is thereby fed to the deep-reaching reaction vessel for the downflow of the deep well reactor, the so-called "down comer", and moved in the downward flow in the depth.

In the downward flow reducing conditions are met, so that once the necessary temperatures and pressures are reached, the HTC of the biomass suspended in the starting mixture can take place. In particular, the process and deepwell reactor are designed such that no additional oxygen is supplied to the starting mixture in the downward flow. Downstream, the HTC of the biomass essentially becomes particulate, carbon-rich compounds. The depth of the deep well reactor and the flow rate of the starting mixture are chosen so that the necessary temperatures and pressures can act on the starting mixture over a period of time sufficient to achieve the desired degree of carbonization of the biomass. Preferably, the downflow is brought down to a depth of at least 200 meters before the upflow starts up, more preferably at a depth of at least 300 meters, most preferably at a depth of 300 meters to 350 meters.

After the downflow has reached the predetermined depth, the resulting reaction mixture is again moved upwardly in an upward flow. For this purpose, the deep well reactor with the "down comer" fluid-conductive upwardly leading reaction vessel for the upward flow, the so-called "up-comer", wherein the "up-comer" is designed such that so that from the "down -comer "in the depth escaping reaction mixture into the" up-comer "convertible and in the upward flow is leitleitbar. In the upward flow, oxygen-containing fluid is added to the reaction mixture obtained, so that in the ascending reaction mixture dissolved organic compounds, eg. B. unwanted hydrolysis products such as organic acids, phenols and furans or higher molecular weight condensation products, can be implemented by wet oxidation and / or degradable. The oxygen-containing fluid may be, for example, an oxygen-containing gas, e.g. B. pure (technical) oxygen, air or mixtures thereof or oxygen in bound form, z. B. as hydrogen peroxide (H ₂ O ₂ ). In this case, the oxygen-containing fluid is added to the ascending reaction mixture in the upward flow at a depth at which the reaction mixture has a temperature and is exposed to a pressure which allows and promotes wet oxidation of organic compounds dissolved in the reaction mixture. Preferably, the oxygen-containing fluid is added to the rising reaction mixture at a depth at which the reaction mixture has a temperature of at least 200 ° C and / or a pressure of at least 1.6 MPa.

The supply of oxygen in the upward flow, in particular of oxygen-containing gases, not only allows an effective wet oxidation of undesirable, dissolved in the reaction mixture organic compounds, but also increases the buoyancy of the three-phase mixture in the reaction mixture comprising water, particulate carbon-rich compounds and gas bubbles and thus supports the flow regime in deep shaft reactor.

From the ascending in the upward flow or the already ascended reaction mixture, the particulate biochars are separated, optionally collected, dried and fed to a further use or storage. The separation of the carbon-rich particles from the reaction mixture can be carried out for example by filters. Suitable filter techniques are known to those skilled in the art.

The remaining process water is dissipated and z. B. a further purification in a biological purification stage are supplied to reduce, for example, difficult to oxidize residues or remove such. B. short-chain carboxylic acids. The combination of wet oxidation and biological treatment stages is well known in the field of wastewater treatment and the skilled person has no difficulty in choosing and using suitable biological purification processes which complement each other advantageously with the wet oxidation carried out.

Alternatively or additionally, at least parts of the process water obtained, if appropriate without additional purification steps, for the preparation of starting mixture (aqueous biomass suspension) can be reused and thus recycled. If it is intended to recycle the process water and reuse it to provide the starting mixture, a certain amount of process water should be withdrawn from the circuit at regular intervals. This is necessary because during HTC water is formed and released, so-called. Excess water from chemical reactions and native moisture of the biomass used, and thus the volume of water in the cycle is constantly increasing. Regular removal of a certain amount of process water ensures that the water volume in the circuit does not increase unchecked. The water to be discharged can be either as a liquid or as a vapor be removed. The removal of liquid prevents at the same time an uncontrolled salination of the process water. The removal of steam leads to its condensation to a weakly polluted wastewater, which can be easily disposed of via a biological treatment stage.

Thus, the inventive method or the deep well reactor according to the invention can be designed such that the O ₂ -containing fluid is added only to a portion of the ascending in the upward reaction mixture. For this purpose, a corresponding part of the reaction mixture can be taken or branched off from the upward stream and then oxygen is added to this branched-off part of the reaction mixture for the purpose of wet oxidation. The withdrawn portion may preferably be a portion of the reaction mixture that is substantially equal to the amount of water released during HTC of the biomass.

Although the particulate, carbon-rich compounds are oxidized much slower than the organic compounds dissolved in the process water. To further increase the quality and yield of the particulate carbon-rich compounds obtained, they may be separated from the rising reaction mixture and removed before oxygenated fluid is added to the process water obtained. This can be achieved, on the one hand, by passing the entire upward flow through a filter which removes the particulate, carbon-rich compounds from the rising reaction mixture before subsequently adding oxygen to initiate the wet oxidation of the organic compounds dissolved in the remaining ascending process water. In another embodiment of the method according to the invention, only part of the ascending reaction mixture is taken from the upflow. From this removed portion of the reaction mixture, the particulate, carbon-rich compounds are separated, for. B. through a filter at the inlet of the extraction line, and then the resulting process water is added oxygen. The remaining, not taken, rising reaction mixture is not added with oxygen and thus exposed to non-oxidizing conditions. In a particularly preferred embodiment of this process, the withdrawn portion of the reaction mixture substantially corresponds to the amount of water released during the HTC of the biomass.

The method and the deep well reactor according to the invention which is suitable for carrying it out can be designed in such a way that the heat released in the HTC and / or wet oxidation is used to heat the starting mixture in the downward flow and to bring it to the desired temperature for the HTC in good time , Alternatively, or additionally, the released heat may be used to dry the particulate carbon-rich compounds obtained during the HTC.

• – ein in die Tiefe führendes Reaktionsgefäß für den Abwärtsstrom, der sogenannte ”down-comer”, wobei der ”down-comer” derart ausgeführt ist, dass dem ”down-comer” Ausgangsgemisch zuführbar und im Abwärtsstrom in die Tiefe leitbar ist;
• – ein mit dem ”down comer” Fluid-leitend verbundenes aufwärts führendes Reaktionsgefäß für den Aufwärtsstrom, der sog. ”up-comer”, wobei der ”up-comer” derart ausgeführt ist, dass damit aus dem ”down-comer” in der Tiefe austretendes Reaktionsgemisch in den ”up-comer” überführbar und im Aufwärtsstrom nach oben leitbar ist;
• – eine Vorrichtung zur Einbringung von sauerstoffhaltigem Fluid in den Aufwärtsstrom im ”up-comer”, wobei die Vorrichtung zur Einbringung von sauerstoffhaltigem Fluid bevorzugt steuer- und/oder regelbar ausgeführt ist.

The deep well reactor according to the invention for carrying out the process according to the invention is characterized in that the deep well reactor has:

• A down-flow reaction vessel, the so-called "down-comer", wherein the "down-comer" is designed such that it can be fed to the "down-comer" starting mixture and can be conducted downwards in the downward direction;
• An upflow reactor connected to the downcomer in a fluid-conducting manner, the so-called "up-comer", wherein the "up-comer" is designed in such a way that it comes from the "down-comer" in the Deep exiting reaction mixture in the "up-comer" convertible and in upward flow can be conducted upwards;
• - An apparatus for introducing oxygen-containing fluid in the upward flow in the "up comer", wherein the device for introducing oxygen-containing fluid is preferably designed to be controlled and / or regulated.

The "down comer" serves as the reaction vessel only the HTC of biomass contained in the starting mixture, while the "up comer" is designed as a reaction vessel both for a HTC and for performing a wet oxidation.

In a preferred embodiment, the "down comer" may be formed as an inner tube, while the "up comer" sheathed the "down comer" as an outer tube. With this arrangement it is achieved that the hot reaction mixture ascending in the "up comer" releases its excess heat to the starting mixture flowing out in the inner tube and heats it, so that the desired conditions for the HTC are achieved there in the "downcomer". The temperature in the downwardly and upwardly flowing reaction medium is determined, in addition to the depth, in particular by the exothermic evolution of heat of the effluent HTC and by the heat exchange between the inner and outer tubes. In addition, the deep well reactor according to the invention can have a cooling jacket, so-called "cooling jacket", which can be operated with cooling medium and drawn off via the excess heat energy and, if appropriate, can be further utilized above ground. The cooling jacket can, if necessary, z. B. for starting the HTC process, also be used as a heating jacket to set the necessary for an autothermal or exothermic start temperatures.

The device for introducing oxygen-containing fluid in the up-comer in the up-comer can be designed, for example, as a gassing lance and ends at a depth with the up-flow release opening in the up comer and temperatures and pressures in the up comer mixture which promote and permit wet oxidation of organic compounds dissolved in the reaction mixture. Preferably, oxygen-containing fluid is added to the upcomer at a depth at which the rising reaction mixture has a temperature of at least 200 ° C. and / or a pressure of at least 1.6 MPa.

If only part of the upward-flowing reaction mixture is to be subjected to wet oxidation, the deep-shaft reactor in the "up comer" can have a removal line for taking off the reaction mixture from the upward flow. Preferably, the removal line is designed such that only a small portion of the reaction mixture is taken up, while the larger portion remains in the upward flow, is transported upwards and there the particulate, carbon-rich compounds are separated. In this case, the device for introducing O ₂ -containing fluid is preferably designed and positioned such that the oxygen-containing fluid is introduced exclusively into the removal line and not into other areas of the deep well reactor, in particular not in the "down comer" or other Areas of "up comer" as the sampling line. This is to ensure that only the part of the ascending reaction mixture withdrawn through the withdrawal line is mixed with oxygen and subjected to wet oxidation. The parts of the reaction mixture which are not taken up in the withdrawal line are transported further up in the "up comer" and are not brought into contact with oxygen.

At the opening for receiving reaction mixture from the "up comer" of the extraction line, a separation device, for. B. a particulate filter, be provided, which is designed and arranged so that thereby a transfer of suspended in the reaction mixture particulate, carbon-rich compounds from the "up comer" in the interior of the sampling line is essentially suppressed, while a transfer of dissolved in the reaction mixture organic compounds in the interior of the sampling line without restriction is possible.

The particulate filter at the inlet of the sampling line has a limited capacity. If exhaustion or clogging appears, it can be flushed out by briefly reversing the direction of flow in the sampling line.

In the following the invention will be explained in more detail by means of exemplary embodiments.

Characters:

1 shows a first embodiment of the deep well reactor according to the invention for carrying out the method according to the invention, wherein the entire upflowing reaction mixture oxygen is added.

A. Embodiments:

Example 1:

The raw biomass 1 , z. B. biogenic residues such as beet pulp, spent grains, pomace or sewage sludge is in the crusher 5 crushed and suspended in process water, the process water recycled process water 4 (HTC water). The degree of comminution and solids content are adjusted so that a sufficiently fluid suspension 8th arises. If necessary, this suspension 8th a catalyst 3 , z. As an organic or inorganic acid added. The suspension 8th is with slight overpressure as entry 6 in the inner tube 19 (down comer) of the deep well reactor fed and flows down there. It is by the in the hull tube 20 (up comer or riser) upstream flowing, heated hot reaction mixture. As the temperature increases, the exothermic HTC reaction sets in, which in turn leads to further heating of the suspension 8th contributes. With increasing depth, the pressure in both tubes of the reactor increases at the same time, so that evaporation of the water can be avoided.

At the lower end of the reactor is the turning point. The reaction mixture flows in the shell tube 20 upwards. The HTC reaction continues. It delivers solid carbon particles and as by-products hydrolysis products (eg, organic acids, phenols, and furans, as well as higher molecular weight products) that remain dissolved in the process water.

The temperature in the reaction medium flowing upwards and downwards is determined by the exothermic evolution of the HTC reaction which takes place and by the heat exchange between the inner tube 19 and sheath tube 20 certainly. In addition, the deep well reactor has a cooling jacket 17 (Cooling jacket) with cooling water 14 can be charged and over the hot water 13 or wet steam can be deducted. Over the cooling jacket 17 a large part of the surplus heat is extracted, which can be reused above ground.

The HTC reaction aims at the formation of biochar and, if necessary, the destruction of pollutants adhering to the starting material. The simultaneous formation of dissolved in water, predominantly low molecular weight organic compounds is undesirable, but unavoidable for chemical reasons.

After separation of the biochar 16 by filtration in the filters 11 can the organically loaded suspension water 4 again to suspend the raw biomass 1 used and so basically recycled, so be recycled. However, the HTC reaction provides water as a reaction product (excess water), so that always an equivalent amount has to be discharged from the water cycle.

The method according to the invention includes two options for solving this problem:
In variant a), pure (technical) oxygen is injected into the ascending product stream at a specific depth (ie at a specific temperature) by means of a gassing lance 10 , The oxygen leads to the wet oxidation of dissolved organic compounds. At the same time, the buoyancy of the three-phase mixture - water, biochar, gas bubbles - is increased and thus the flow regime is supported. The wet oxidation is exothermic. The excess heat is transferred to the inner tube 19 and the cooling jacket 20 and improves the energy balance of the overall process. Wet oxidation eliminates much of the dissolved organic compounds. Hardly oxidizable residues, eg. As short-chain carboxylic acids such as acetic acid, oxalic acid, etc., are in a subsequent biological purification stage 2 further reduced. The combination of wet oxidation and biological waste treatment is a well-known principle based on the rule of experience, according to which different degradation mechanisms (here chemical and biological oxidation) complement each other favorably.

Also, under the conditions of wet oxidation, the conversion of the HTC reaction in the particulate material progresses in the direction of the formation of biochar. The deep well reactor is therefore utilized simultaneously and optimally for two different chemical reactions. This simultaneous reaction is inventively made possible by the fact that in the first part of the reactor - in the inner tube 19 - First, a "stabilization" of the feedstock (biomass) by carbonation takes place and only at a suitable location in the second part of the reactor - at a suitable depth in the shell tube 20 - The wet oxidation is initiated.

Variant a) is based on the different oxidation rates of dissolved (DOC = dissolved organic carbon) and particulate organic compounds (POC = particulate organic carbon). Carbon particles are oxidized more slowly than most dissolved organic compounds. However, this difference depends on the specific ingredients used and the quality of the intended end product. Under aggravated reaction conditions (higher temperatures, longer reaction times) more strongly carbonized biochars are formed, while humic-like products are formed under mild reaction conditions. The latter are still relatively easy to oxidize. For this reason, it may be desirable not to subject them to an oxidizing reaction milieu to avoid product losses and improve the carbon yield of the HTC process.

Example 2:

Therefore, in variant b), the upwardly flowing product stream is in the casing tube 20 separated. The larger proportion is transported without oxygen contact up and separated there by filtration. The separated, organically contaminated water is completely recycled. A smaller partial flow, the z. B. corresponds to the excess water formed is in the shell tube 20 via a particle filter 21 withdrawn separately and fumigated with oxygen 10 , The wet oxidation takes place in variant b) analogously to variant a), but only for a partial stream which is largely free of carbon particles. The corresponding pre-cleaned water 9 is as in variant a) a biological treatment 2 fed. The particle filter 21 at the entrance of the oxidation tube has only a limited capacity. For this reason, a quick, periodic backflushing of the filter by the above-ground in the engine house pump 7 intended. The backwash transports the separated biochar back into the main product stream.

In a further embodiment of variant b) is applied to the particulate filter 21 waived. The wet oxidation then takes place for this partial stream without particle separation. The main stream does not come in contact with oxygen. A small loss of biochar can be accepted because of the preceding mass flow division into main and secondary flow.

• – Eine einfache und kontinuierliche Reaktionsführung mit einer Niederdruck-Dosierung von festoffhaltigen Produktströmen in einen Hochdruckreaktor und
• – eine integrierte Behandlung der organisch hoch belasteten Reaktionswässer durch Nassoxidation.

The process according to the invention solves two main problems of the HTC reaction:

• - A simple and continuous reaction with a low-pressure metering of festoffhaltigen product streams in a high pressure reactor and
• - an integrated treatment of the organically highly loaded reaction waters by wet oxidation.

In most processes, chemical reactions and the treatment of waste products are carried out in separate process stages. The inventive feat of the concept described above exists u. a. in that reactor and reaction conditions during the HTC reaction directly for the purification of the water phase to use - and this, although the applied reactions (HTC and wet oxidation) very different reaction milieu - reducing or oxidizing - require.

LIST OF REFERENCE NUMBERS

1

Raw biomass / bio

2

biological treatment

3

Catalyst (if necessary)

4

recycled HTC water (80%)

5

crush

6

entry

7

pump

8th

suspension

9

oxidized HTC water (20%)

10

O ₂ injection

11

filtration

12

discharge

13

hot stream

14

cold water

15

earth plane

16

biochar

17

cooling jacket

18

O ₂ injection (variable position)

19

down comer

20

riser tube

21

Particulate filter for separation of DOC and POC (if required)

22

Diameter reactor 0.3 m (V _R = 0.25πd ² L = 70 m ³ )

23

1000 m / 100 bar / T _max ~ 310 ° C

Claims (15)

Process for the hydrothermal carbonization of biomass in a deep shaft reactor, wherein: - a flowable starting mixture is provided which comprises biomass suspended in water and optionally one or more catalysts or consists thereof; - The starting mixture is fed to a deep well reactor; and - reducing conditions are followed in the downstream direction, which allow the hydrothermal carbonization of the biomass contained in the descending starting mixture to particulate, carbon-rich compounds; characterized in that - in the upward flow to the resulting reaction mixture oxygen-containing fluid is added, so that in the ascending reaction mixture dissolved organic compounds by wet oxidation can be implemented. The method of claim 1 wherein the particulate carbonaceous compounds are separated from the ascending or ascending reaction mixture and the remaining process effluent is removed. Process according to claim 2, wherein at least parts of the process water are reused for the production of starting mixture. The process of claim 1, 2 or 3 wherein oxygen-containing fluid is added to only a portion of the ascending reaction mixture. The method of claim 4, wherein the portion of the ascending reaction mixture to which oxygen-containing fluid is added substantially corresponds to the amount of water released during the hydrothermal carbonization of the biomass. Method according to one of the preceding claims, wherein at least a portion of the reaction mixture, to which oxygen-containing fluid has been added, is fed to a biological purification stage after wet oxidation. A process according to any one of the preceding claims wherein, of the portion of the ascending reaction mixture to which oxygen-containing fluid is to be added, the particulate carbon-rich compounds are substantially separated before the oxygen-containing fluid is added. Method according to one of the preceding claims, characterized in that molecular oxygen (O ₂ ), preferably as technically pure oxygen, or chemically bound oxygen, preferably as hydrogen peroxide, are used as oxygen source. Method according to one of the preceding claims, wherein the heat released in the hydrothermal carbonation and / or the wet oxidation is used to heat the starting mixture in the downward flow and / or to dry separated organic compounds. A method as claimed in any one of the preceding claims, wherein the downflow is reduced to a depth of at least 200m before the upflow begins, preferably at a depth of at least 300m and more preferably at a depth of 300m to 350m. Method according to one of the preceding claims, wherein the oxygen-containing fluid is added to the ascending reaction mixture at a depth at which the reaction mixture has a temperature of at least 200 ° C and / or a pressure of at least 1.6 MPa. Deep well reactor for carrying out a method according to one of claims 1 to 11, wherein the deep well reactor: - has a down-flow reactor, the so-called "down-comer", wherein the "down comer" carried out in such a way is that the "down-comer" feedstock feedable and in the downward flow in the depth can be conducted; and - an upflow reactor connected in a fluid-conducting manner with the "downcomer", the so-called "up-comer", wherein the "up-comer" is designed in such a way that it can be removed from the "down-comer" in the depth escaping reaction mixture in the "up-comer" convertible and in upward flow can be conducted upwards; characterized in that - the deep well reactor has a device for introducing oxygen-containing fluid in the upward flow in the "up comer". Deep-shaft reactor according to claim 12, wherein in the "up-comer" a removal line for removal of reaction mixture from the upward flow is contained. Deep well reactor according to claim 13, wherein the device for introducing oxygen-containing fluid is designed and positioned such that the oxygen-containing fluid can be supplied to the ascending reaction mixture exclusively in the withdrawal line. Deep shaft reactor according to claim 13 or 14, wherein at the inlet of the extraction line, a separation device is provided, which is designed and arranged such that thereby a transfer of suspended in the reaction mixture particulate carbon-rich compounds from the "up comer" in the interior of the extraction line substantially can be prevented, while a transfer of dissolved in the reaction mixture of organic compounds in the interior of the extraction line is essentially not suppressed.

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