METHOD FOR PRODUCEING A WOOD FIBER AND WOOD FIBER PRODUCE DEVICE

Description

[0001] The invention relates to a method for producing a wood fiber material, comprising the steps (a) heating wood chips in a pre-cooker using water or steam, (b) then cooking the wood chips using steam in a cooker (14), and then (c) fiberizing the wood chips in a refiner to produce fiber material, wherein (d) a portion of the steam is diverted after fiberizing and used to heat or cook the wood chips.

[0002] According to a second aspect, the invention relates to a wood fiber manufacturing device for producing wood fiber material, comprising (a) a pre-cooker for heating wood chips using water or steam, (b) a cooker arranged downstream of the pre-cooker in the direction of wood material flow (H) for cooking the wood chips using steam, so that cooked wood chips are produced, (c) a refiner arranged downstream of the cooker in the direction of wood material flow (H) for fiberizing the cooked wood chips, so that fiber material is produced, (d) a steam branch arranged downstream of the refiner in the direction of wood material flow (H) for diverting a portion of the steam after fiberization, and (e) an exhaust steam line connecting the steam branch to the pre-cooker or cooker for supplying steam to the

[0003] Wood fiber materials are produced from wood and are used, for example, in the manufacture of wood fiberboards or insulation material. The production of wood fiber requires large quantities of steam. WO 2015 / 014451 A1 describes a generic process in which steam is extracted from the fiber-steam stream by means of a cyclone downstream of the refiner.

[0004] The partial diversion of steam downstream of the refiner and its use for heating or cooking wood chips is also known from US Patent 4,925,527. To prevent volatile organic compounds present in the wood from accumulating in the wood fibers, a portion of the steam is condensed, the terpene-rich components are separated, and the heat released during condensation is used to evaporate water. This process is complex and energy-inefficient. Therefore, there is a desire to reduce energy consumption.

[0005] From CA 2346915 A1, a process is known for purifying gases generated during the Kraft process in the pretreatment with black liquor, boiling in white liquor, washing and separation of the pulp from the black liquor, ratification of volatile organic components with superheated steam, delignification, washing and bleaching of the pulp, and combustion and regeneration of the black liquor. These gases are extracted by ventilation. They are oxidized with air or ozone as an oxidizing agent at a temperature of no more than 100°C under heterogeneous catalysis. Such a process is not feasible with the steam that can be diverted after fiberization because of its saturation with water vapor, as condensation of the water would occur at the aforementioned low temperatures.

[0006] The invention is based on the objective of reducing disadvantages in the prior art.

[0007] The invention solves the problem by means of a method having the features of claim 1.

[0008] The invention also solves the problem by means of a wood fiber manufacturing device with the features of claim 8.

[0009] An advantage of the invention is that it allows the production of wood fiber material, for example in the production of wood fiberboards such as LDF, MDF, or HDF, with lower energy consumption. Because the diverted steam is purified, it can be used in the process without terpenes and / or aldehydes accumulating in the wood fiber material. If the steam were not purified, volatile organic substances contained in the diverted steam, particularly terpenes and / or aldehydes, would deposit on the wood chips, thus increasing the concentration of these volatile organic substances in the wood fiber material, which is undesirable. Furthermore, purifying the steam generally prevents the volatile organic substances from depositing on the exhaust steam line, through which the diverted steam is carried away from the steam diversion point.

[0010] For the purposes of this description, a steam cleaner is understood to be a device by means of which a VOC concentration (volatile organic compounds), in particular terpenes and / or aldehydes, can be reduced by at least 70% by chemical reaction of the volatile organic compounds with an oxidizing agent.

[0011] Cooking wood chips specifically means heating them with water and / or steam. The wood chips are first placed in the pre-cooker, then in the cooker.

[0012] Steam is understood to be a mixture of vaporous water and air, especially water vapor.

[0013] The term wood fiberboard refers in particular to LDF, MDF or HDF.

[0014] Instead of "cooked wood chips," one could also speak of "heated wood chips."

[0015] Preferably, the oxidizing agent is a flameless oxidizing agent. According to one embodiment, the oxidizing agent contains oxygen. It is advantageous if the oxidizing agent releases elemental oxygen upon reaction with terpenes and / or aldehydes.

[0016] The oxidizing agent is ozone or hydrogen peroxide. When hydrogen peroxide is mentioned, this also includes an aqueous solution of hydrogen peroxide. The hydrogen peroxide may contain an iron(II) salt, ammonium persulfate, cytochrome P450, monooxygenases, or ammonium peroxide. In particular, the oxidizing agent is non-molecular oxygen or air.

[0017] It is advantageous that the diversion of steam, and in particular the diverted steam mass flow, can be independent of the type of wood chips used. It is especially advantageous that a mass flow control of the diverted steam, as provided for in a preferred embodiment, can be independent of the type and / or properties of the wood chips used. This simplifies the control of the wood fiberboard manufacturing device. Instead, the oxidizing agent volume flow can be controlled to ensure that a predetermined maximum concentration of volatile organic substances is always kept below a specified maximum.

[0018] According to a preferred embodiment, the wood chips are heated in the pre-cooker using purified steam. For this purpose, the wood chips are brought into contact with the steam, for example, before cooking and fiberization.

[0019] It is advantageous to continuously measure the VOC concentration, i.e., the concentration of volatile organic compounds, especially terpenes and / or aldehydes, in the diverted steam. The VOC concentration is expressed, for example, as mass per volume of steam or as a mass fraction of the steam. The VOC concentration is understood to be a concentration from which the concentration of volatile organic components can be inferred. In particular, the TOC concentration of all organic carbon compounds is also a VOC concentration when it comes to complying with an upper limit. When the VOC concentration is mentioned below, it could also be used more generally to refer to the TOC concentration (TOC = total organic carbon).

[0020] Preferably, the introduction of the oxidizing agent into the diverted steam is controlled based on the VOC concentration. In other words, the amount of oxidizing agent, specifically the oxidizing agent flow rate, introduced into the diverted steam is increased when the VOC concentration rises. Conversely, the amount of oxidizing agent introduced into the diverted steam can be reduced when the VOC concentration falls. This ensures that, on the one hand, a sufficient amount of oxidizing agent is always introduced into the diverted steam, and on the other hand, that oxidizing agent consumption is minimized. It is advantageous if this VOC concentration is measured upstream of the injection point where the oxidizing agent is introduced into the diverted steam.

[0021] According to one embodiment, a second VOC concentration of volatile organic substances, in particular terpenes and / or aldehydes, is continuously measured in the diverted steam. Preferably, the introduction of the oxidizing agent into the diverted steam is also controlled or regulated based on this second VOC concentration.

[0022] For example, if the second VOC concentration rises above a predetermined maximum concentration, the amount of oxidizing agent introduced per unit of time (oxidizing agent flow rate) is increased according to a preferred embodiment. This occurs even if the first VOC concentration does not change.

[0023] If the second VOC concentration falls below a predetermined minimum concentration, the oxidizing agent flow is reduced according to a preferred embodiment. This occurs particularly even if the first VOC concentration does not change.

[0024] Typically, a fiber-steam mixture exits the refiner. According to a preferred embodiment, a maximum of 40% by mass of the steam in the fiber-steam mixture is diverted. Diverting more steam usually makes conveying the fiber material more difficult.

[0025] Alternatively or additionally, at least 10 percent by mass of the steam in the fiber material-steam mixture is diverted. This results in a significant saving of energy that would otherwise be required to generate the steam. The figures given are, for example, average values ​​over 10 minutes.

[0026] According to one embodiment, the method comprises the step of irradiating the oxidizing agent with UV light. This, for example, causes the oxidizing agent to form radicals, particularly hydroxyl radicals. Preferably, the irradiation of the oxidizing agent with UV light takes place immediately before it is introduced into the diverted vapor. In particular, the distance between the point where the oxidizing agent is irradiated with UV light and the point where the oxidizing agent first comes into contact with the diverted vapor is at most 10 m, and more particularly, at most 5 m.

[0027] Preferably, the diverted vapor has a vapor temperature of at least 110°C when the oxidizing agent is introduced. At higher temperatures, the oxidizing agent reacts more quickly with the volatile organic substances, resulting in lower concentrations of these substances in the purified vapor. It is advantageous if the vapor temperature is no more than 160°C. At even higher temperatures, the oxidizing agent generally decomposes too quickly.

[0028] Preferably, the diverted steam has a pressure of at least 2 bar and / or at most 5 bar.

[0029] Preferably, the method comprises the step of applying adhesive, in particular by means of a blow line, to the wood fiber material and drying the adhesive fiber material. It is advantageous if the method includes the steps of spreading the, in particular dried, adhesive fiber material into a fiber cake and pressing the fiber cake to form a wood fiberboard. Pressing is carried out, for example, by means of a belt press.

[0030] In one embodiment, the steam cleaner includes an injection device for introducing the oxidizing agent into the steam line, by means of which diverted steam from the steam cleaner is discharged. For example, the injection device is designed to inject or atomize the oxidizing agent.

[0031] The steam cleaner can have an oxidizer tank filled with an oxidizer, for example, hydrogen peroxide. Preferably, the steam cleaner also has a pump for conveying the oxidizer to the dispensing device. Alternatively or additionally, the steam cleaner can have an oxidizer generator by means of which the oxidizer can be produced. For example, the oxidizer generator can be an ozone generator. Alternatively or additionally, the steam cleaner can have an oxidizer container in which the oxidizer can be stored. The oxidizer container is filled with hydrogen peroxide or ozone.

[0032] It is advantageous if the wood fiberboard manufacturing device has a VOC concentration meter for measuring a (first) VOC concentration of volatile organic substances, especially terpenes / or aldehydes, and / or the total concentration of organic carbon compounds in the vapor in the direction of vapor flow upstream of an injection point where the oxidizing agent is introduced into the diverted vapor.

[0033] The dosing unit is preferably designed to automatically introduce the oxidizing agent into the diverted vapor based on the measured VOC concentration. In other words, the dosing unit controls or regulates the oxidizing agent flow rate. For example, the dosing unit includes a controllable pump and / or a controllable valve for this purpose.

[0034] The VOC concentration meter comprises, for example, a gas chromatograph with a flame ionization detector. The VOC concentration meter is preferably configured for automatic measurement of the VOC concentration at regular intervals, for example, more frequently than once per hour, particularly more frequently than once every half hour, and most preferably more frequently than once every 10 minutes.

[0035] Preferably, the wood fiber production device also includes a flow meter for measuring the steam flow of diverted steam. The steam flow can be specified, for example, in mass per unit time or volume per unit time. It is advantageous if the steam branch is designed to divert a predetermined steam flow. For example, the steam branch has a valve that is controlled by a regulator, the regulator being connected to the flow meter. In this way, the valve is controlled so that a predetermined target steam flow is always maintained.

[0036] In a preferred embodiment, the dosing unit is configured to detect the VOC concentration from the VOC concentration meter and to automatically introduce the oxidizing agent into the diverted steam based on the VOC concentration and the steam flow rate. In other words, the volumetric flow rate of oxidizing agent to be introduced into the diverted steam per unit time is calculated, particularly based on the VOC concentration and, optionally, the steam flow rate, and then the oxidizing agent is introduced accordingly.

[0037] The wood fiber manufacturing device preferably has a first injection device for introducing the oxidizing agent into the diverted steam at a first injection point.

[0038] It is particularly advantageous if the steam cleaner is designed to regulate the VOC concentration to a predetermined target concentration. If the measured VOC concentration deviates from the target concentration, the oxidizing agent flow rate is adjusted so that the measured VOC concentration approaches the target concentration. If the measured VOC concentration is above the target concentration, the oxidizing agent flow rate is increased. If the measured VOC concentration is below the target concentration, the oxidizing agent flow rate is decreased.

[0039] According to a preferred embodiment, the wood fiber production device has a second VOC concentration meter for measuring a second VOC concentration (or a second TOC concentration) in the diverted steam downstream of the injection point, wherein the metering device is configured to automatically introduce the oxidizing agent into the diverted steam based on the first VOC concentration and the second VOC concentration, and optionally the steam flow rate. In other words, the metering device is configured to control or regulate the oxidizing agent volume flow rate based on the first and second VOC concentrations.

[0040] The wood fiber production device preferably has a second injection device for introducing the oxidizing agent into the diverted steam at a second injection point located downstream of the first injection point in the steam flow direction. Preferably, the second injection point is located downstream of the second VOC concentration meter. It is advantageous if the steam cleaner is designed to control a second oxidizing agent volume flow rate, which is introduced at the second injection point, depending on the second VOC concentration.

[0041] It is particularly advantageous if the steam cleaner is designed to regulate the second VOC concentration to a predetermined target concentration. If the measured second VOC concentration deviates from the target concentration, the first and / or second oxidizing agent flow rate is adjusted so that the measured second VOC concentration approaches the target concentration. If the measured second VOC concentration is above the target concentration, the first and / or second oxidizing agent flow rate is increased. If the measured second VOC concentration is below the target concentration, the first and / or second oxidizing agent flow rate is decreased.

[0042] Preferably, the wood fiber manufacturing device includes an edge banding unit for applying glue to the fiber material. An edge banding unit is understood to be a device by means of which the fiber material can be glued.

[0043] Preferably, the wood fiberboard manufacturing device is part of a wood fiberboard manufacturing device according to the invention for producing lightweight, medium-density fiberboard (LDF), medium-density fiberboard (MDF), and / or high-density fiberboard (HDF). According to the invention, this also includes a wood fiberboard manufacturing device for producing a wood fiberboard, in particular an MDF board, comprising (a) a cooker for cooking wood chips with steam to produce cooked wood chips, (b) a refiner arranged downstream of the cooker in the direction of wood material flow to break down the cooked wood chips into fiber material, and optionally (c) a gluing unit, in particular a blow line, arranged downstream of the refiner in the direction of wood material flow to apply adhesive to the fiber material, resulting in glued fiber material.In the direction of wood material flow behind the refiner and before the edge bander, in particular a blow line, a steam branch is arranged for diverting steam and the wood fiber manufacturing device has a steam cleaner which is designed to introduce an oxidizing agent into the steam so that volatile organic substances contained in the steam are oxidized and purified steam is produced.

[0044] A wood fiberboard is understood to be a board manufactured using wood. Preferably, the wood fiberboard has a thickness between 2 mm and 60 mm. Preferably, the density of the wood fiberboard is between 600 kg per cubic meter and 1000 kg per cubic meter. The wood chips are preferably wood shavings.

[0045] Gluing can be carried out, for example, using a blow line. The edge banding unit is preferably positioned downstream of the steam branch in the direction of wood material flow.

[0046] The invention will now be explained in more detail with reference to the accompanying drawing. This drawing shows Figure 1 shows a flowchart of a wood fiberboard manufacturing device according to the invention for carrying out a method according to the invention, and Figure 2 shows a flowchart of a wood fiberboard manufacturing device according to the invention for carrying out a method according to a second embodiment.

[0047] Figure 1Figure 1 shows a flow diagram of a wood fiber production device 10 according to the invention for producing wood fiber 11. The wood fiber production device 10 has a cooker 14 which receives wood chips 18 heated by a pre-cooker 16. The wood chips 18 were cleaned by a washing system 24 before being introduced into the pre-cooker 16. A refiner 32 is arranged downstream of the cooker 14 in the direction of wood material flow H, by means of which the wood chips 18 coming from the cooker 14 are broken down into fibers. Together with steam 26, this produces a steam-fiber mixture 38.

[0048] Steam 26 is extracted from the steam-fiber material mixture 38 via a steam branch 36 and fed into an exhaust steam line 69. A steam cleaner 52 is arranged in the exhaust steam line 69. The steam cleaner 52 functions as described below in connection with Figure 2 described.

[0049] The steam-fiber material mixture 38 can be fed to an edger 40, which is preferably designed as a blow line, but this is not necessary. The steam-fiber material mixture 38 is fed to a dryer 44, from which steam 26 and dried wood fiber material 11 exit.

[0050] The wood fiber material 11 is used, for example, for the production of insulation material, medium-density fiberboard (MDF), lightweight medium-density fiberboard (LDF), high-density fiberboard (HDF), plant substrate for plant cultivation, such as potting soil, or packaging material.

[0051] Figure 2 The flowchart shows a wood fiberboard manufacturing device 10 according to the invention for producing a wood fiberboard 12 in the form of an MDF board.

[0052] The pre-cooker 16 is fed with wood chips 18, which are produced, for example, by a chipper 20 and subsequently washed, if necessary, in the washing plant 24. Round timber 22 can be used as raw material, but other sources of wood are also possible. In the pre-cooker 16, the wood chips 14 are heated with hot water and / or steam 26'. The water or steam 26' can be generated by a boiler. From the pre-cooker 16, the heated wood chips 18 enter the cooker 14.

[0053] In the direction of wood material flow H downstream of the cooker 14, the resulting steam-wood chip mixture 30 enters the refiner 32, where the fiber material 34 is produced. Downstream of the refiner 32 in the direction of wood material flow H is the steam diverter 36, by means of which the steam 26 can be diverted. For example, 20 to 30 percent by mass of the steam contained in the steam-fiber material mixture 38 is diverted.

[0054] The remaining steam-fiber mixture 38 is fed to a blow line 40 and coated with adhesive. The resulting coated fiber material 42 is then fed into a dryer 44, where it is dried. The dried fiber material 42 is then fed to a spreader 46, which spreads a fiber cake 48. The fiber cake 48 is pressed into a wood fiberboard 12 by means of a press 50.

[0055] The steam cleaner 52, arranged downstream of the steam branch 36 in the direction of steam flow D, introduces an oxidizing agent 56 into the branched steam 26 at an injection point 54. In this case, the oxidizing agent is hydrogen peroxide.

[0056] The steam cleaner 52 comprises an oxidizing agent source 58, which in this case includes an oxidizing agent container 58 and a metering device 60 in the form of an oxidizing agent pump. Using a VOC concentration meter 62, the steam cleaner 52 measures an initial VOC concentration cVOC,1 of volatile organic compounds in the diverted steam 26. Depending on the VOC concentration, an oxidizing agent volume flow rate Q56 of oxidizing agent 56 is introduced into the diverted steam 26 by means of an injection device 57, for example, by spraying. The oxidizing agent 56 reacts with volatile organic compounds in the diverted steam.

[0057] The steam cleaner 52 can have a second VOC concentration meter 64, which is located downstream of the inlet point 54 in the steam flow direction D. The second VOC concentration meter measures a second VOC concentration cVOC,2. In this case, it is the TOC concentration of the total organic compounds. If the second VOC concentration cVOC,2 is above a predetermined maximum concentration cVOC,max, the oxidizing agent volume flow rate Q56 is increased.

[0058] The steam cleaner 52 regulates the second VOC concentration c VOC,2 to a VOC target concentration c VOC,target by increasing or decreasing the oxidizing agent volume flow Q 56.

[0059] Alternatively, the steam cleaner 52 may have an injection device, for example a nozzle 66, for introducing oxidizing agent at a second injection point 54' downstream of the second VOC concentration meter 64 in the steam flow direction D. Alternatively, the oxidizing agent volume flow rate Q 56 may be increased if the second VOC concentration c VOC,2 is above the maximum concentration c VOC,max. It is possible, but not necessary, for the same oxidizing agent to be introduced at both injection points 54 and 54'. In particular, it is possible for two different oxidizing agents to be used.

[0060] By introducing the oxidizing agent, purified steam 68 is produced, which is supplied to the preboiler 16 by means of an exhaust line 69.

[0061] The steam cleaner 52 can have a light source 74 by means of which the oxidizing agent 56 can be irradiated with UV light. In this way, hydroxyl radicals are formed, which destroy the volatile organic substances in the diverted steam 26 particularly effectively.

[0062] At the in Figure 2 In the wood fiberboard manufacturing device 10 shown, for example, 2.5 ±0.5 t of steam per hour are diverted from steam branch 36. Instead of diverting, one can also speak of diverting.

[0063] A vapor temperature T26 is, for example, 140°C ± 5°C. The first VOC concentration meter 62 measures an initial VOC concentration of cVOC,1 = 350 mg / m³. The oxidizing agent flow rate is then set to Q56 = 125 liters / hour. The oxidizing agent 56 in this case is a 10% (weight percent) hydrogen peroxide solution. The second VOC concentration meter 64 then measures a second VOC concentration of cVOC,2 = cTOC,2 = 30 mg / m³. This corresponds to a reduction of over 90%. Reference symbol list 10 Wood fiberboard manufacturing device 60 Add-in dispenser 11 Wood fiber material 62 first VOC concentration meter 12 wood fiberboard 14 cooker 64 second VOC concentration meter 16 Pre-cooking 18 (Hack)schnitzel 66 second insertion device, second nozzle 20 hacker 68 purified steam 22 Round timber 69 Exhaust pipe 24 Car wash 26 steam 70 Branch valves 72 capacitor 30 Steam-wood chip mixture 74 light source 32 Refiner c VOC,1 first VOC concentration 34 Fiber material c VOC,2 second VOC concentration 36 Steam branch c VOC,max Maximum concentration of volatile organic compounds (VOCs) 38 vapor-fiber material mixture 40 Blow-line, edging c VOC, should VOC target concentration 42 Glued fiber material D Steam flow direction 44 dryer H Wood current direction 46 Spreader Q 56 oxidizing agent volume flow 48 Fiber cake T 26 Steam temperature 50 press 52 Steam cleaner 54 Point of entry 54' second injection point 56 oxidizing agent 57 Insertion device, first nozzle 58 Oxidant container

Claims

1. A method for producing a wood fibre material comprising the steps (a) heating wood chips (18) in a pre-boiler (16) by means of water or steam (26), (b) then boiling the wood chips (18) in a boiler (14) by means of steam (26), (c) subsequently defibering the wood chips (18) in a refiner (32), resulting in fibre material (34), (d) wherein part of the steam is branched off after defibering and used to heat or boil the wood chips (18) in the pre-boiler (16), characterised by the step (e) introducing an oxidising agent (56) into the branched-off steam (26) so that volatile organic compounds contained in the steam (26) are oxidised, resulting in purified steam (68), wherein the purified steam (68) is at least partially used to heat the wood chips (18) (f) wherein the oxidising agent is hydrogen peroxide or ozone.

2. The method according to claim 1, characterised by the steps: (a) continuously measuring a VOC concentration (cVOC,1) of volatile organic compounds, especially terpenes and / or aldehydes, in the branched-off steam (26) and (b) controlling the introduction of the oxidising agent (56) into the branched-off steam (26) on the basis of the VOC concentration (cVOC,1).

3. The method according to one of the preceding claims, characterised by the steps: (a) continuously measuring a second VOC concentration (cVOC,2) of volatile organic compounds, especially terpenes and / or aldehydes, in the branched-off steam (26) and (b) controlling the introduction of the oxidising agent (56) into the branched-off steam (26) on the basis of the second VOC concentration (cVOC,2).

4. The method according to one of the preceding claims, characterised in that (a) the refiner (32) releases a fibre material-steam mix (38) and (b) a maximum of 40 percent by mass and / or a minimum of 10 percent by mass of the steam (26) in the fibre material-steam mix (38) is branched off.

5. The method according to one of the preceding claims, characterised by the step irradiating the oxidising agent (56) with UV light such that the oxidising agent (56) forms radicals.

6. The method according to one of the preceding claims, characterised in that, when the oxidising agent (56) is being introduced, the branched-off steam (26) (a) has a steam temperature (T26) of 110°C to 160°C and / or (b) has a pressure of at least 2 bar and / or at most 5 bar.

7. The method according to one of the preceding claims, characterised by the steps (a) glueing the fibre material (34) in a gluer (40), especially a blow line, resulting in glued fibre material (42), (b) scattering the glued fibre material (34) to produce a fibre cake (48) and (c) pressing the fibre cake (48) to form a wood fibre panel (12).

8. A wood fibre material production device for producing a wood fibre material with (a) a pre-boiler (16) for heating wood chips (18) by means of water or steam (26), (b) a boiler (14) arranged downstream of the pre-boiler (16) in the direction of wood material flow (H) for boiling wood chips (18) by means of steam (26) (c) a refiner (32) arranged downstream of the boiler (14) in the direction of wood material flow (H) for defibering the boiled wood chips (18), resulting in fibre material (34), (d) a steam branch (36) arranged downstream of the refiner in the direction of wood material flow (H) for branching off part of the steam (26) after defibering and (e) an exhaust steam line (69) that connects the steam branch (36) to the pre-boiler (16) for supplying steam (26), characterised by (f) a steam purifier (52) that is configured to introduce an oxidising agent (56) into the steam (26), causing volatile organic compounds contained in the steam (26) to be oxidised and resulting in purified steam (68) (g) wherein the oxidising agent is hydrogen peroxide or ozone.

9. The wood fibre material production device according to claim 8, characterised by (a) a VOC concentration gauge (62) for measuring a VOC concentration (cVOC,1) of volatile organic compounds especially terpenes or aldehydes, in the branched-off steam (26) upstream of an introduction point (54) in the direction of steam flow (D) where the oxidising agent (56) is introduced into the steam (26), and (b) a doser (60) that is designed to automatically introduce the oxidising agent (56) into the branched-off steam (26) on the basis of the VOC concentration (cVOC,1).

10. The wood fibre material production device according to one of the claims 8 or 9, characterised by (a) a second VOC concentration gauge (64) for measuring a second VOC concentration (cVOC,2) in the branched-off steam (26) downstream of the introduction point (54) in the direction of steam flow (D), (b) wherein the doser (60) is designed to automatically introduce the oxidising agent (56) into the branched-off steam (26) on the basis of the first VOC concentration and the second VOC concentration.

11. The wood fibre material production device according to one of the claims 8 to 10, characterised by an introduction device (66) that is designed to automatically introduce the oxidising agent (56) into the branched-off steam at a second introduction point (54') that is located downstream in the direction of steam flow (D) from where the second VOC concentration (cVOC,2) is measured.

12. The wood fibre material production device according to one of the claims 8 to 10, characterised by (a) a gluer (40), especially a blow line, arranged downstream of the refiner (32) in the direction of wood material flow (H) for glueing the fibre material (34), resulting in glued fibre material, (b) a dryer (44) arranged downstream of the gluer (40) in the direction of wood material flow (H) for drying the glued fibre material (34), (c) a scatterer (46) for scattering dried fibre material (34) to produce a fibre cake (48) and (d) a press (50), especially a belt press, for pressing the fibre cake (48) to form a wood fibre panel (12).