Apparatus and process for generating energy carriers from wet biomass

p0001The present invention is concerned with the energy technical utilization of wet biomass, particularly of cereals and especially corn.

p0002The energy-related use of dry cereal is practiced sporadically, but encounters e-pathic reservations, as it could in theory be used for human consumption. Feucht cereals harvested, which is conventionally used only for animal feed, not encountered such reservations. So needed maize, which is grown in many parts of Europe as animal feed, often allows a longer growing season than the air to mature. He must therefore damp, be harvested in an unsuitable for human consumption quality.

p0003One problem with the use of biomass energy technology of any kind, is its water content. A high water content affects the shelf life of the biomass, resulting in high transport costs, reduces energy yield when burning and affects the exhaust gas quality. Drying of the biomass in the open air takes much time and large areas, and drying by heating often requires more energy than can be generated by the combustion of the dry biomass.

p0004Out <patcit id="pcit0001" dnum="DE102004003011A1"><text>DE 10 2004 003 011 A1</text></patcit> discloses a generic device with a drainage device for mechanical Vorentwässern of biomass and a drying step for machentwässern the dewatered biomass by heating. Again, from the application depends on primary energy, which is needed to make the biomass for further processing to the direct or indirect use as an energy source useful, critical of the degree of attainable with the mechanical dewatering means dewatering and the efficiency of the dryer stage.

p0005Object of the present invention is therefore to provide a technique that makes it possible with a minimum of energy to dehydrate in a short time in a compact plant wet biomass such an extent that it is technically usable energy in an economical manner.

p0006The object is achieved firstly by the fact that in an apparatus for energy recovery from wet biomass of the above type dewatering device comprises a first dewatering stage and a second dewatering step, which is combined with the drying step in an assembly. The division of the dewatering unit reflects the fact that the freshly harvested biomass usually has a water content of 80% or above, and that by Albtrennung a substantial portion of this water significantly decreases the throughput of material, the consistency of the material but significantly changes simultaneously. The division may take this into account by making the two drainage levels for significantly different material throughputs are designed according to the mass loss by taking place in the first stage drainage, and by different, adapted in each case to the consistency of the material techniques and / or processing parameters in the first and second dehydration step are used. In that the second dewatering step, which can be designed more compact than the first due to the decreased to unmanageable amount of material is combined with the drying step in an assembly, a compact construction is achieved, is minimized in the due to short by way of expenditure of energy for the conveying of the material.

p0007Preferably, the drying step includes a simultaneously dewatered with the biomass and a heat transfer material can be charged mixing tank. By the biomass is in the mixing vessel with the Wärmeträgerimaterial in direct contact, more efficient and more rapid heat exchange is possible than in each heat exchanger, which performs in a conventional manner Märmeträgermaterial and material to be heated in separate lines.

p0008Advantageously, the device includes a separation stage for separating the heat transfer material from the nachentwässerten biomass. Due to the separation stage, the heat transfer material can be recovered in order to be subsequently reheated and fed to drying vorentwässerter biomass again. The separation step is preferably integrated in the assembly of the second dehydration step and the drying step.

p0009The heating of the drying step is preferably carried out over a cycle of Märmeträgermaterials extending through a heat source, the drier stage and the separation stage.

p0010Preferably, the heat transfer material is combustible. So does not affect a permanent back in nachentwässerten biomass residue of the heat transfer material whose energy-related use. On the contrary, it can improve the handling properties of nachentwässerten biomass by allowing them to clump dense chunks.

p0011To effektivieren the dewatering of the biomass in the second dehydration step, is preferably between the first dewatering stage, and the second dehydration step, a grinding step for grinding the biomass, after passing through the first dewatering stage rescheduled. By means of the first dewatering stage initially weakly bound in the cell assembly of biomass Dasser is eliminated and only then the biomass is crushed, a material is obtained whose cellular structure is broken up by the loss of water in the first dewatering stage. Water, which is released in the second step of dehydration from the cells of the biomass can relatively easily penetrate into the previously obtained free spaces of the cell association to a sectional area of ​​the corresponding biomass piece and eventually exit therefrom.

p0012Preferably, the first dewatering stage comprises at least one pair of pressing rollers defining a traversed by the biomass press nip.

p0013The second dewatering step preferably comprises a decanter or a screw press, both of which are suitable for rapid processing of large amounts of crushed material.

p0014A heater may be provided to heat the second dewatering stage continuous biomass. The heating includes the cell structure of the material to continue, thus facilitating additional drainage. Since this heating only the further disruption of the cells of the biomass is used, but not to vaporize the remaining moisture, the power requirement of the heater is small compared to the heating that would be required to dry the biomass by evaporation.

p0015In particular, the drying step may be due to the close proximity to the second dehydration step at the same time serve as the heating means mentioned above, wherein the heating of the harvested material during the passage of the second dehydration step can be achieved at virtually no cost in that the dryer stage is such thermally insulated so that the adjacent second dewatering stage comprises Wiesentfels union draining-off forms, via the penetrating the heat from the drying step into the open.

p0016The apparatus may further comprise a reactor for thermochemical treatment of the dried biomass in the dryer stage. In such a reactor at a high temperature exothermic processes such as the carbonization of biomass make it possible to heat the drier stage substantially with waste heat, in this case with the of the reactor.

p0017The heat supply to the drying step takes place by hot reaction product of the reactor is supplied as a heat transfer material. Since the reaction products leaving the reactor is generally at a high temperature, it is generally desirable to cool a reaction product before it is fed to a tank for storing, and by the reaction product is used as a heat transfer material in the drying stage, his already dissipated residual heat can be used wisely ,

p0018It may be expedient to feed hydrogen gas into the reactor to reduce the residual oxygen content of the reaction products contained therein, or adjust the hydrogen / carbon ratio of these reaction products and thus the length of their carbon chains to a desired value.

p0019To obtain the · hydrogen can serve an electrolysis stage, the electrolyzed deposited in the dewatering device liquid.

p0020In order to collect in the reactor as vapor liberated reaction products, a condensation step is preferably provided. This is also water, collected, which is either added to the biomass or created in the reactor and that affects the quality of the condensate. To rid a product obtained in the condensation stage water-rich condensate of hydrocarbon fractions, the condensate can be passed through a filter, which can be charged as a filter material also herrührendem from the reactor coke. In this way, purified water can be discharged from the mechanical dewatering stages directly to the field, as excess water. The filters in saturated with organic constituents Coke can - be returned to the reactor - directly or indirectly.

p0021Gaseous reaction products, particularly those of non-condensable remain after passing through the condensation stage, distortion as self genatzt in harvesting vehicle as an energy source, in particular in a burner for heating the reactor.

p0022It may further include a concentration step may be provided which receives the separated in at least one of the stages of dehydration aqueous portion to these gange enriched in a solute and to divorce a depleted solute content. will be collected in a tank of the harvesting vehicle During the enriched fraction in general for further processing, the depleted fraction is preferably as mentioned above discharged onto the pitch.

p0023In particular, the drying step may be due to the close proximity to the second dehydration step at the same time serve as the heating means mentioned above, wherein the heating of the harvested material during the passage of the second dehydration step can be achieved at virtually no cost in that the dryer stage is such thermally insulated so that the adjacent second dewatering stage Wiesentfels union draining-forms, via the penetrating heat from the dryer step outside.

p0024Further features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. Show it:<dl id="dl0001"><dt>Fig. 1</dt><dd>a schematic representation of processing means of a device according to the invention; and</dd><dt>FIG. 2</dt><dd>a detail from <figref idrefs="f0001">Fig. 1</figref>,</dd></dl>

p0025In the <figref idrefs="f0001">Fig. 1</figref> shown and described in detail below for devices are incorporated into a harvesting vehicle according to a preferred embodiment of the invention. An exterior view of the harvesting vehicle is not inclined, as its external shape, so far as it does not resemble that of a conventional combine or forage harvester, is only dictated by the requirement that in<figref idrefs="f0001">Fig. 1</figref> devices shown accommodate it. Akin to a conventional forage harvester or combine has the harvesting vehicle, a chassis to which a Erntegutaufnehmer is front mounted interchangeably. The Erntegutaufnehmer is identical to that of a conventional forage harvester or combine harvester and used interchangeably in this as well as the harvesting vehicle according to the invention.

p0026Two nip rolls 1 forming a nip to which the Ge biomass is conveyed by the pick. When passing between the nip rolls 1, the biomass loses depending on the plant, about half of its water; nourishing the proportion of dry matter contributes in the freshly inducted biomass varies between 10 and 30%, the proportion by passage through the nip rolls 1 is increased to 18 to 46%.

p0027The dewatered using compression rollers 1 biomass then passes through a chopping 2, which may comprise as a forage harvester, a rotating knife drum and cooperating therewith stationary knife. The shredding is more intense than with a forage harvester, for example, because of closer to the knives or increased residence time of the biomass in the chopping step 2, so that receive the output of chopping particles with a typical maximum size of 4 mm.

p0028The comminuted material from the chopping step 2 is subjected to a second dewatering stage 3, for example a decanter or a sieve centrifuge. In combination with the intensive fragmentation, this enables an increase in the dry matter proportion of 88-98 percent. Thus, a fibrous, cellulose-rich solid is obtained whose mass makes up only about 10 to 30% of the originally recorded biomass.

p0029The 3 output from the second dewatering stage dewatered material goes through a drying step 7, and a separation step 9, before it is fed to a flash pyrolysis reactor 6th By heating the absence of air in the reactor 6 the feed material is converted into a continuous process in water, various hydrocarbons and an essentially consisting of carbon, known as coke residual solids. The at the high temperature of the reactor 6 released as a gas reaction products are a condensation stage supplied 8 and condensed into fractions with different boiling points. In condensation step 8 non-condensable gas fed to a burner 16 which heats the reactor. 6

p0030In condensation step 8 fractional condensation takes place, wherein parameters of the fractionation are defined such that a fraction substantially all 6 registered and contains the biomass in the reactor, the water produced by the pyrolysis therein, while at least one other fraction, as product referred oil substantially consisting of only hydrocarbons. The product oil obtained is collected in a tank 10, with the exception of a part, preferably a condensing at high temperature fraction, which is wholly or partly branched off from the condensation stage 8 so as to be added in the drying step 7 of the dewatered biomass from the second dehydration step 3 ,

p0031The drying stage 7 can kneading or mixing tools have for mixing of the product oil with the dehydrated biomass. The high temperature of the product oil brings the residual moisture in the biomass to evaporate, so that a mixture of product oil and substantially anhydrous biomass at the outlet of the drying stage 7 can be withdrawn.

p0032This mixture passes through before it reaches the reactor 6, a separator stage 9, in which the product oil is separated again under pressure from the biomass. The separated product in this way oil is collected together with the non-drying stage 7 supplied proportion of the product oil from the condensation stage 8 in the tank 10th

p0033A preferred development according to purifying the obtained in condensation step 8, consisting essentially of water condensate fraction, a filter 11 is provided. As the filter substrate, filter 11 uses a portion of the coke from the reactor 6, which is continuously fed through the filter 11 in countercurrent to the aqueous fraction and thereby saturating the organic constituents of the aqueous fraction. The water obtained by the filtering can - if necessary, after a post-cleaning - are deposited onto the field; saturated with the organic content of coke can be collected together with the residual coke from the reactor 6 in a bunker 12 as fuel, or it may - depending on the degree of saturation with water or with organic material - directly into the reactor 6, as in of the<figref idrefs="f0001">Fig. 1</figref> be represented, or attributed to the detour via the drying stage 7 to the reactor 6 distill the organic components and to add to the product oil.

p0034The second dehydration step 3, the drying step 7 and the separation stage 9 are in a in <figref idrefs="f0002">FIG. 2</figref> schematically illustrated common assembly summarized. All three stages are housed together directly bordering on a common thermally insulating sheath 18th Rotating screws or blades of the three stages, as illustrated, be driven uniformly about a common shaft 19, or it may at any stage, a separate motor may be associated with, and have the steps 3, 7, 9 are each independent of each other and with a the amount and consistency of each step of material adjustable speed driven shaft pieces.

p0035The dewatering step 3 has a frustoconical chamber in which a screw 20 is rotated and thereby the biomass pressed or spun against a wall 21 of the chamber. The wall 21 is pierced like a sieve on a large part of their surface so that from the biomass squeezed moisture, the wall 21 passes and passes via an outlet 22 to the concentration level. 4 On other parts of the wall 21 a Märmetauscherrohr 23 is distributed, which is shown schematically as a single extending around the dewatering stage 3 pipe loop in the figure, but in reality may comprise a plurality of loops. The screw 20 promotes the biomass through the dehydration step 3 through to an exit on a small base of the truncated cone-shaped chamber, to which the drying step 7 immediately follows.

p0036The drying stage includes a cylindrical or barrel-like container 17, in which a screw or vane assembly 24 transporrund the material it over pipeline 25 at the upstream end of the reservoir 17 eingespeistem hot product oil from the reactor 6 kneaded.

p0037The fed with a temperature of typically 200 to 250 ° C product oil brings in the biomass contained residual water in a very short time largely to evaporate. At the output of the drying step 7, a substantially anhydrous material flow is obtained that it has a mushy consistency to chunky depending on the quantity ratio of biomass and product oil.

p0038Said material passes through the separation step 9, the construction can be largely identical to the second dewatering stage 3 in principle. Instead of Masser the product oil is extracted again in the separation stage 9, and the product thus recovered oil passes via an outlet 26 and the heat exchanger 23 in the (in<figref idrefs="f0002">FIG. 2</figref> not shown) Tank 10th

p0039The drying stage 7 or in <figref idrefs="f0002">FIG. 2</figref> Arrangement shown of the steps 3, 7, 9 is applicable also to a harvesting vehicle with a simplified structure, in which the reactor 6 is absent. In this case, the vehicle performs in place of the reactor 6, an oil storage tank, and any means for heating the oil from this tank by itself to supply the drying step 7 with hot oil. In the separation stage 9 again separated oil is returned to the tank or heated immediately again in order to be added to the biomass supplied from the dewatering step 3 again.

p0040Oil losses resulting from an incomplete separation in the separation stage 9, are not overly troublesome because the 9 is not redeposited oil increases in the separation stage the calorific value of 9 output from the separation stage dry biomass and this is a highly condensed, Chunky, easy to handle consistency gives.

p0041The separated in the dewatering stages 1 and 3 water could be discharged directly to the area of ​​arable land in the simplest case. Suitably, however, is contained cultivable ingredients such as sugars, proteins, starches, lipids, acids or mineral substances in a concentration stage 4, for example, a membrane filter or a plurality of series such filters to separate. Using known filtration techniques as an enriched with valuable ingredients electricity are produced with a dry matter content of up to 80 percent and of the valuable constituents substantially freed Nasser, which is discharged onto the pitch.

p0042In a drying step, the solids content in the enriched stream can be increased to up to 90 percent. The concentrate thus obtained is collected in a tank 15 on board the harvesting vehicle for further use, such as feed, as raw material for the chemical industry or as raw material for fermentation processes to produce biogas or ethanol.

p0043One further development of the invention according to an electrolytic cell 13 is provided, which is fed with the enriched fraction from the concentration step. 4 The electrolytic cell 13 is supplied with a frequency modulated DC, for a high yield of hydrogen to achieve and lower power consumption. Hydrogen obtained from electrolysis is fed into the pyrolysis reactor. 6 The thus achieved increase of the hydrogen supply in reactor 6 improves the implementation of the bound in the biomass oxygen to water, so that an oxygen-poorer and therefore higher quality oil from the flash pyrolysis is obtained.

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p0044<dl id="dl0002" compact="compact"><dt>1</dt><dd>dewatering stage</dd><dt>2</dt><dd>chopping</dd><dt>3</dt><dd>dewatering stage</dd><dt>4</dt><dd>concentration level</dd><dt>5</dt><dt>6</dt><dd>pyrolysis reactor</dd><dt>7</dt><dd>drying stage</dd><dt>8th</dt><dd>condensation stage</dd><dt>9</dt><dd>separation stage</dd><dt>10</dt><dd>tank</dd><dt>11</dt><dd>filter</dd><dt>12</dt><dd>bunker</dd><dt>13</dt><dd>electrolytic cell</dd><dt>14</dt><dt>15</dt><dd>tank</dd><dt>16</dt><dd>burner</dd><dt>17</dt><dd>container</dd><dt>18</dt><dd>shell</dd><dt>19</dt><dd>wave</dd><dt>20</dt><dd>slug</dd><dt>21</dt><dd>wall</dd><dt>22</dt><dd>expiration</dd><dt>23</dt><dd>heat exchanger tube</dd><dt>24</dt><dd>vane assembly</dd><dt>25</dt><dd>pipeline</dd><dt>26</dt><dd>expiration</dd></dl>