• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A process for the production of wood pellets from wood chips, comprising a drying step (5), a separation step (8) for rejecting unwanted fractions, and a pelleting step (10), wherein the undesired fractions separated in the separation step (8) are sent to combustion; released combustion heat (VW) the drying step (5) is recycled. According to the invention, in the drying step (5), a first drying takes place in a first dryer (5.1), and a second drying takes place in a second dryer (5.2) following the first dryer. With the aid of the two-stage dryer system according to the invention, uniform drying of the mixed wood chips is ensured, and the energy efficiency of the pelleting plant is increased. By adding the flue gas (R) into the drying process, the efficiency of the entire system can be increased and the emissions of the system can be reduced.
    公开号:AT510925A1
    申请号:T80242011
    申请日:2010-12-16
    公开日:2012-07-15
    发明作者:
    申请人:Schoerkhuber Feurer Maria；
    IPC主号:
    专利说明:

    • »* MM < tl * ·· »*« M »« F / L00202 ** · »I · · · * · ·» * * * * * * ··· ** · · · · · «*» * # | "····"· 1
    The invention relates to a process for the production of wood pellets from wood chips, comprising a drying step, a separation step for the separation of undesired fractions, and a pelletizing step, wherein the separated in the separation step, undesired portions of a combustion 'supplied', and the released combustion heat is returned to the drying step , according to the preamble of claim 1.
    With the proliferation of wood pellet heaters, the demand for wood pellets, which were initially made from bark-free sawing by-products, also increases. Due to the shortage of these raw materials, wood chips are increasingly being used, which is available comparatively cheaply in large quantities. However, the use of wood chips as starting material requires a corresponding adaptation of the production process, in particular with regard to the comminution, drying and separation of the starting material. The additional x-reduction and drying steps also increase the energy requirements of the entire system, so that an energy-efficient design of the system must be ensured.
    It is therefore the object of the invention to optimize a process for the production of wood pellets from wood chips so that the energy consumption of the pelletizing plant is lowered. In this way, the production of wood pellets from wood chips should also be more attractive in economic terms.
    These objects are achieved by the features of claim 1. Claim 1 relates to a method for the production of wood pellets from wood chips, comprising a drying step, a separation step for the separation of undesirable fractions, and a pelletizing step, wherein the separated in the separation step, unwanted portions of a combustion are supplied, and. released combustion heat is recycled to the drying step. According to the invention, it is proposed that in the drying step in a first dryer, a first 2
    Drying takes place, and in a second dryer following the first dryer, a second drying takes place.
    In a conventional manner, only a single dryer is used, which is dimensioned according to the amount of wood chips. Due to the use of a second dryer, two different types of dryers can be used in order to meet different drying requirements. Thus, for example, in a drum dryer, a first, rapid drying to a precisely predefined moisture content, and a further reduction to a, necessary for the further process flow moisture content in a subsequent Wälzbetttrockner. This makes it possible to increase the energy efficiency of the system significantly, especially in plants where drying heat from a combustion of separated components of the wood chips is used. In these cases, the available heat must be used optimally, as will be explained in more detail. Due to the new heat circulation between the two dryers, a higher throughput of material to be dried can be achieved with less energy consumption. Of course, it would also be conceivable to use more than two dryers.
    Furthermore, due to the serial arrangement of two dryers, a thermal cycle between the two dryers can be realized by returning heat from the subsequent second dryer to the first dryer. For this purpose, it is essential to the invention that the second dryer follows the first dryer, and the two dryers are therefore arranged in series. The entire drying material must therefore pass through both dryers.
    In order to further increase the energy efficiency of the overall system, it is further proposed that the combustion heat released in the combustion of the separated, undesired fractions is supplied to an ORC process before being returned to the drying step. The ORC process ("Organic Ranking Cycle") is based on a similar process to the water-steam process 3 with the difference that instead of water, an organic working medium, such as hydrocarbons such as iso-pentane, iso-octane, toluene or Silicone oil, is used. This working medium has more favorable evaporation properties at lower temperatures and pressures, and is therefore particularly suitable for the postcurrent of industrial waste heat. For the purpose of the Nachverstromung the resulting heat of combustion via heat exchangers and the working medium circuit is transferred to the ORC system. The ORC system generates electrical energy which can be used to cover the requirements of the pelleting plant or for feeding it into the public power grid. In addition, low-temperature waste heat is generated, which can be used as low-temperature process heat for drying by returning it to the first dryer and the second dryer. The use of two serially arranged dryers, between which heat can be circulated, thereby facilitating the. optimum use of this low-temperature waste heat.
    It is also advantageous if the recirculated waste heat are added to the liberated in the combustion flue gases. This increases the efficiency of the plant due to a lower heat requirement for drying, and the emission values of the entire system are significantly improved.
    Furthermore, it is proposed that the pelletizing heat released in the pelleting step be recycled to the first dryer and the second dryer. In the course of pelleting, namely, heat is released, which can be used for drying. In most cases, the actual pelleting is followed by a cooling process of the pelleted material. The heat energy withdrawn here is also referred to as pelletizing heat and returned to the first and second dryer. 4
    The invention will be explained in more detail below with reference to an embodiment with reference to the accompanying figures
    Fig. 1 is a flow chart for a possible embodiment of a pelleting process according to the invention, and the
    2 shows a flow chart for selected method steps according to FIG. 1.
    Reference is first made to Fig. 1, which shows a flow chart for a possible embodiment of a pelleting process according to the invention, which may of course also vary according to local conditions or process requirements. In this case, via a delivery 1, possibly via an intermediate storage, logs of all varieties unsorted and sometimes even poorer quality bereifgestellt. The delivery 1 can be made by a vehicle fleet of the plant operator, or by the forest owner himself. In principle, all types of wood can be used, only restrictions are that no leaves and no needles may be present.
    In a weighing station 2, the delivered raw material is weighed and tested for its moisture content. In a first crushing step 3, the delivered wood is comminuted to different chips size, mixed and fed through the task 4 the actual process process. Initially erfindungsgeraäß a first drying takes place in a first dryer 5.1, and then a second drying in a second dryer 5.2. In the first dryer 5.1, such as a drum dryer, the wood chips are dried to a predefined moisture content. The pre-dried material is then dried in a second dryer 5.2, such as a Wälzbetttrockner, to the moisture content necessary for the further procedure. Roller bed dryers work with heat in the
    Low-temperature range. The heat transfer is ensured by the dense arrangement of scoop-like Ennbauten 5. With the aid of the two-stage dryer system according to the invention, uniform drying of the mixed wood chips is ensured. in a first separation step 6 there is a separation of
    Foreign matter and wood chips, optical or mechanical separation step is crushing step 7 crushing step 7 which can be done depending on the type of foreign matter. After the first, the wood chips fed to a second. After the second will be in a second
    Separation step 8 mechanically separated unwanted particles from the fiberized wood. The unwanted fractions are combustible, non-pelletable fractions in the dried wood chips, in particular bark fractions.
    The dried, furred wood is processed .in a ripening container 9 for the subsequent pelleting 10.
    The separated bark portions in the form of bark dust are burned in a biomass boiler 17, wherein an increased wood chips feed 20 is possible with increased energy requirements. By means of a cogeneration unit 18, in the exemplary embodiment shown an ORC system, the heat of combustion VW released in the biomass boiler 17 is converted into electrical power, which can be fed into a power grid 19. This generated electricity can be used for the self-consumption of the pelleting plant, or in the public network as so-called "green electricity". be fed, whereby the efficiency and energy efficiency of the system is significantly improved. The heat of combustion VW generated by the biomass combustion is first transferred via a thermal oil boiler to the ORC process. Thermo-oil is preferably used as the working medium, since it can achieve the temperatures required for the operation of the ORC process, and at the same time a virtually pressureless boiler operation is possible, so that no boiler warden is required. The heat transferred from the thermal oil to the ORC process evaporates the organic working medium used. The steam passes to a slow-running axial turbine, in which it performs mechanical work under relaxation in a vacuum, which generates electrical energy in the generator coupled directly to the turbine. The expanded steam is fed to a regenerator for internal heat recovery, which increases the electrical efficiency. Subsequently, the working medium vapor enters the condenser. Finally, the condensate is returned to operating pressure via a pump and fed to the evaporator. This closes the ORC cycle.
    The waste heat KW of the ORC process can be supplied to the first dryer 5.1 and the second dryer 5.2. The flue gas R emerging from the thermal oil boiler, which originates in particular from the combustion in the biomass boiler 17, is produced by efficient heat recovery, for example via a
    Combustion air preheater, cooled. Subsequently, the flue gas R is added to the recycled in the first dryer 5.1 and the second dryer b.2 waste heat KW from the ORC process. The addition of the flue gas R into the drying process increases the economic efficiency of the entire system and reduces the emissions of the system.
    After pelleting, the pellets are subjected to cooling 11 and stored. The pellets can then be transported via a loading station 12 directly to specially equipped tank trucks with their own weighing and storage
    Suction system be made available to the large customer 13 loose. The pellets can also in a packing station 15 in specially designed containers as bagged goods for
    Small customers 16 are processed. Furthermore, pellets from each batch are tested in a quality control 14 in their own laboratory for the required quality standards.
    FIG. 2 shows selected method steps according to FIG. 1 for explaining the heat recovery. 7
    Shown in particular are the delivery 1, the first dryer 5.1, the second dryer 5.2, the second crushing step 7, the second separation step 8, in which combustible, non-pelletable fractions in the dried wood chips, in particular bark fractions, are mechanically separated from the fiberized wood, as well the combustion of these unwanted components in the biomass boiler 17, and the subsequent utilization of the heat of combustion VW in the context of cogeneration 18 in the ORC system. The bold arrows in the left half of the diagram symbolize the material flows. In the right half of the diagram, by contrast, the energy flows and the recirculation of the flue gas R are drawn with thinner arrows. It can be seen in particular from FIG. 2 that the waste heat KW from the ORC plant is returned to the first dryer 5.1, as well as to the second dryer 5.2. In this case, the recirculated waste heat KW can be added to the flue gas R released in the course of combustion in the biomass boiler 17. Furthermore, the pelletizing heat PW released in the course of pelleting can also be recycled to the first drier 5.1 and to the second drier 5.2. The inventive measure of the second, serially arranged dryer 5.2 also offers the advantage, between the first dryer 5.1 and the second dryer 5.2 to realize an additional heat cycle by drying heat TW from the second dryer 5.2 is returned to the first dryer 5.1.
    With the aid of the two-stage dryer system according to the invention, uniform drying of the mixed wood chips is ensured. and increases the energy efficiency of the pelleting plant. The addition of the flue gas R in the drying process increases the efficiency of the entire system, and reduces the emissions of the system.
    权利要求:
    Claims (6)
    [1]
    · Μ · ·

    Claims 1. A process for the production of wood pellets from wood chips, comprising a drying step (5), a separation step (8) for rejecting unwanted fractions, and a pelleting step (10), wherein the undesired fractions of combustion separated in separation step (8) are fed, and the released combustion heat (VW) is returned to the drying step (5), characterized in that in the drying step (5) in a first dryer (5.1), a first drying takes place, and in a first dryer following, the second dryer ( 5.2} a second drying takes place.
    [2]
    2. The method according to claim 1, characterized in that drying heat (TW) from the second dryer (5.1) is recycled to the first dryer (5.1).
    [3]
    3. The method according to claim 1 or 2, characterized in that the combustion heat released in the combustion of the separated, unwanted fractions (VW) before their return to the drying step (5) is fed to an ORC process.
    [4]
    4. The method according to claim 3, characterized in that the waste heat (KW) from the ORC process the first dryer (5.1) and the second dryer (5.2) is recycled.
    [5]
    5. The method according to claim 3 or 4, characterized in that the recirculated waste heat (KW) which are released in the combustion flue gases (R) are added.
    [6]
    6. The method according to any one of claims 1 to 5, characterized in that in the pelletizing step (10) • * · · * * · · · · ······································································. The released pel- leting heat (PW) is returned to the first dryer (5.1) and the second dryer (5.2).

    Vienna, 1 Dec. 6, 2010
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    同族专利:
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    AT510925B1|2013-08-15|
    引用文献:
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    法律状态:
    2016-08-15| MM01| Lapse because of not paying annual fees|Effective date: 20151216 |
    优先权:
    申请号 | 申请日 | 专利标题
    AT80242011A|AT510925B1|2010-12-16|2010-12-16|PROCESS FOR PRODUCING WOOD PELLETS|AT80242011A| AT510925B1|2010-12-16|2010-12-16|PROCESS FOR PRODUCING WOOD PELLETS|
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