EP2616530A2

EP2616530A2 - Method and device for producing a solid fuel from biomass

Info

Publication number: EP2616530A2
Application number: EP11813526.8A
Authority: EP
Inventors: Erich SCHÜRMANN
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-09-17
Filing date: 2011-09-19
Publication date: 2013-07-24
Also published as: DE102010045612A1; WO2012048677A2; WO2012048677A3

Abstract

The invention relates to, inter alia, a device for producing a solid fuel from biomass, comprising a biogas system (11), by means of which fermentation residues and biogas can be produced, and a drying system (13) arranged downstream of the biogas system (11) in the material flow direction for drying fermentation residues of the biogas system (11). The invention is characterized in that a torrefaction device (14) is arranged downstream of the biogas system (11) in the material flow direction.

Description

Method and device for producing a solid fuel from biomass

The invention relates to a method and an apparatus for producing a solid fuel from biomass. The digestate should be converted into a valuable fuel. A continuous operation, a simple structure and a high profitability are in the foreground.

STATE OF THE ART

Modern biogas plants with a combined heat and power plant to generate electricity are increasingly equipped or retrofitted with a drying system for the resulting fermentation residues. In these drying systems, the fermentation residues are dried with a TS content of about 5 to 10% to a TS content of about 85% using the waste heat of the combined heat and power plant. The dried fermentation residue then has, depending on the type of dryer, a bulk density of 150 to 350 kg / m ³ , which can be increased by a downstream pelleting to about 650 kg / m ³ .

The fermentation residues can be labeled as fertilizer and have a fertilizer value of approx. 20, - € / t. As fuel, the digestate can only be used to a limited extent. As a fuel, however, a correspondingly prepared and pelleted fermentation residue would be significantly more valuable at about 200 € / t. This economic potential is to be realized with the device according to the invention. A method for producing fuel in a biogas plant is described in DE 10 2008 015 609 A1. The fermentation residue obtained in the process is separated into a liquid fraction and a solid fraction. The solid fraction is suitable after drying as fuel.

CONFIRMATION COPY In US 2009/0250331 A1 a Torrefizierungsvorrichtung and a method for torrefaction are described. As starting material for use in Torrefizierungsvorrichtung and for the process fresh biomass is used, which is previously heated if necessary. The end product after torrefaction can be used as fuel.

WO 2005/056723 A1 describes a method and a device for torrefaction of an organic raw material in order to obtain a fuel.

It was an object of the present invention to provide a method for producing a fuel from biomass, which is improved in terms of its economy.

The object is achieved by a method having the features of claim 1.

The biogas plant is fed biomass. In the biogas plant, biogas is produced from the biomass, resulting in fermentation residues. At least part of the digestate is fed from the biogas plant to the reactor space of a torrefaction device. In the reactor room, the fermentation residues are heated under exclusion of air and thereby torrefiziert, with a solid fuel.

According to one embodiment of the invention, at least part of the fermentation residues of the biogas plant is first fed to a drying plant and then passes from the drying to the reactor space of the Torrefizierungsvorrichtung.

By the treatment according to the invention of the digestate to a fuel of almost ten times the market price compared to the market price for Fertilizer achieved, but without having to do without the inorganic fertilizer substances, as they are basically still available after the energetic use of the fuel in the ashes as fertilizer available. The use of processed fermentation residues as fuel allows a reduction of over-fertilization of the soil.

In some regions with high livestock, there is an oversupply of feed through feed imports. The mineral fertilizer remains in the thermal utilization of the treated digestate in the ash, where it is highly concentrated and transportable. The fuel can be marketed or used locally for the drying of other digestate quantities. With the possibility to produce a transportable and storable fuel two major effects are achieved in addition to the better economy. On the one hand, the energy efficiency of the biogas plants is improved and, on the other hand, local over-fertilization of the fields is prevented. With the method according to the invention, the combustion properties of the resulting fuel are improved and the calorific value is significantly increased. With the method according to the invention, the treatment of the biogas for feeding into a natural gas network to an ecologically rather questionable alternative with respect to the digestate and the fertilizer loads.

Torrefication is a pyrolysis process with a temperature limited to, for example, about 300 ° C. In this case, volatile components escape with a total of only low calorific values, with the dried fermentation residues resulting in a reduction in mass of 10 to 25%, leading to a significant increase in the calorific value of about 4 kWh / kg to 6 kWh / kg. The TS content increases from 85% to approx. 95%. In a biogas plant with combined heat and power plant and connected digestate drying the high temperature level of the exhaust gases of the engine is not used directly for the digestate drying, but only indirectly for heating the dry ambient air according to the current state of the art. Since the exhaust gas temperature of a cogeneration plant with 450 to 500 ° C is higher than the required temperature for torrefaction of Dried fermentation residues, the device for Torrefizierung can be heated with the exhaust gas of the engine. The energy required for Torrefizierung the resulting digestate of a biogas plant at about 300 ° C is measured in terms of the total heat supply of the combined heat and power plant very low.

Since the torrefaction must be done under exclusion of air, the device for torrefaction of the dried fermentation residues is e.g. equipped with a double jacket, which is flowed through by the exhaust gases of the internal combustion engine of the cogeneration plant. The reactor of the Torrefizierungsvorrichtung is in this case with the exhaust gas of the internal combustion engine on e.g. heated about 300 ° C. The hot, volatile outgassings that arise during the Torrefizierung from the digestate are fed to the digestate dryer to assist with the energy of the exhaust gases from Torrefizierung the dryer. In addition, the already existing exhaust air cleaning the digestate drying, e.g. also used for the volatile outgassing of torrefaction.

Object of the present invention, it was also to create a biogas plant with combined heat and power plant, their efficiency is significantly increased. In a biogas plant with a connected combined heat and power plant, a higher quality fuel is to be produced from the dried fermentation residues of the biogas plant.

The object is achieved by a biogas plant having the features of claim 2.

With the system having the features of claim 2, in particular the method according to claim 1 can be carried out. With regard to the advantages of the biogas plant according to claim 2, reference is therefore made to the advantages mentioned in claim 1 (see page 2, last paragraph to page 4, second paragraph).

Further advantages will become apparent with reference to Ausführungsbeispieien shown in the drawings. Show it: 1 is a schematic block diagram of the system according to the invention,

2 shows a schematic sectional view of a first embodiment of the Torrefizierungsvorrichtung the system of FIG. 1,

Fig. 3 is a schematic sectional view of a second embodiment of the Torrefizierungsvorrichtung the system of FIG. 2. In the figures, the inventive device is in total with the

Reference numeral 10 denotes. Like reference numerals in the various figures indicate corresponding parts, even if small letters are added. Fig. 1 shows an embodiment of the device according to the invention

10. In Fig. 1, a biogas plant or a biogas generator 1 1, a combined heat and power plant 12, a drying apparatus 13 for dewatering and drying of the digestate and a Torrefizierungsvorrichtung 14 is shown. The fermentation residues, which are produced during the biogas production in the biogas generator 1 1, are fed by means of a line 17 to the drying apparatus 13 and dried. The biogas generator 11 has a filling device 15 for the biomass, a gas line 16 leading to the combined heat and power plant 12, a fermentation residue line 17 to the drying apparatus 13 and a flow line 18th and a return line 19 for hot water between the combined heat and power plant 12 and the biogas generator 1 1 for heating the biogas generator 11 and between the combined heat and power plant 12 and the drying apparatus 13 for heating the drying apparatus thirteenth The block heating plant 12 comprises a gas engine 20 and a generator 21 and has an exhaust pipe 22 which is connected to a heating jacket 23 of the Torrefizierungsvorrichtung 14. The heating jacket 23 is connected via a line 32 to the drying apparatus 13. With the high exhaust gas temperatures, first the Torrefizierungsvorrichtung 14 is heated. After the exhaust gases have cooled in the torrefaction device 14, the exhaust gases pass via the line 24 to the drying apparatus 13 and are used for drying the fermentation residues.

The Torrefizierungsvorrichtung 14 is heated indirectly with the exhaust gases of the gas engine 20. The heating of the fermentation residues takes place under exclusion of air. The volatile products of Torrefizierung be supplied via a line 32 to the drying apparatus 13 in order to use the heat energy and the compulsory integrated in the drying apparatus 13 gas scrubbing system.

The torrefaction device 14 is e.g. formed as a screw reactor and in this case comprises a tube housing 25 and an internal screw conveyor 26 with a motor drive, not shown. The Torrefizierungsvorrichtung 14 has 5 pieces connection openings, the exhaust gas inlet 27, the exhaust outlet 28, the fermentation inlet 29, the fermentation residue outlet 30 and the outlet 31 for the volatile products of Torrefizierung.

A first embodiment of the Torrefizierungsvorrichtung 14 is shown in Fig. 2. The Torrefizierungsvorrichtung 14 is preferably constructed as a screw reactor and consists of a double-walled tube housing 25 with a rotatable screw conveyor 26 with a drive motor 33. The screw space 34 is, for example, only partially filled with material to achieve a certain mixing effect. The speed of the screw conveyor 26 determines the digestate throughput and the residence time of the material in Torrefizierungsvorrichtung 14. The required residence time is for example in the range of several minutes. The tubular housing 25 is formed as a double jacket 35 and serves as a heat exchanger for heating the device with the exhaust gases of the internal combustion engine. The double jacket 35 has an exhaust gas inlet 27 and an exhaust gas outlet 28 for the exhaust gases of the gas engine 20 of the combined heat and power plant 12.

5 The screw space 34 is gas-tight shut off and has at least three

Openings, an opening for the fermentation residue inlet 29, an opening for the fermentation residue outlet 30 of the torrefizierten digestate and at least one opening for the escape of the volatile exhaust gases 31st The closable opening for the fermentation residue inlet 29 can be realized with a rotary valve 36, with a double flap l o or with a hose valve. The closable opening at the fermentation residue outlet 30 may be a rotary valve 37 or a double flap.

The volatile exhaust gases resulting from the Torrefizierung be either the exhaust gas stream of the gas engine 20 or via the line 32 the

15 dryers 13 for the wet fermentation residues of biogas generator 1 1 supplied. If the exhaust gases from the screw space 34 of the Torrefizierungsvorrichtung 14 supplied to the exhaust gas of the gas engine 20, this can be done via an ejector or with a blower 38. If the exhaust gases supplied to the dryer 13 for the fermentation residues, this can be done with a blower 38. The method can also be applied to other woody biomasses, if according to the invention the exhaust gases of a gas engine 20 are used.

A second embodiment of the Torrefizierungsvorrichtung 14 is shown in Fig. 3. The Torrefizierungsvorrichtung 14 includes a tube housing 25th

25 with a rotatable conveyor screw 26 which is driven by a drive motor 33. The screw space 34 should preferably be only partially filled with material in order to achieve a certain mixing effect. The speed of the screw determines the digestate throughput and the residence time of the material in the torrefaction device. The required residence time is in the range of

30 minutes. The tubular housing 25 comprises double jackets, which serve as heat exchangers for the heating and for the subsequent cooling of the fermentation residues. The first double jacket 39 in the direction of flow serves as a heat exchanger for heating the device with the exhaust gases of the internal combustion engine and has an exhaust inlet 41 and an exhaust outlet 42 for the engine exhaust gases of the cogeneration plant 12. The other double jacket 40 serves to cool the torrefizierten fermentation residues and is of a cooling medium , preferably flows through the engine cooling water and has a coolant inlet 43 and a coolant outlet 44. The screw space 34 is gas-tight shut off and has at least three

Openings, an entry port 45 for the entry of fermentation, a discharge port 46 for the exit of torrefizierten digestate and at least one opening for the escape of volatile exhaust 50. The closable opening for the fermentation entry 45 can with a rotary valve 47, with a double flap or with a hose valve will be realized. The closable opening on the material discharge 46 may be a rotary valve 48 or a double flap.

The volatile exhaust gases resulting from the Torrefizierung be either a combustion system, the gas engine 20 or the drying apparatus 13 for the wet fermentation residues of the biogas plant 1 1 supplied. The exhaust gases are e.g. the drying apparatus 13 for the digestate, e.g. supplied with a blower 49. The method can also be applied to other woody biomasses, if according to the invention the exhaust gases of an internal combustion engine are used.

It should be noted that alternatively to the illustrated embodiment, the first provided for heating double jacket 39 a first tube and the second provided for cooling double jacket 40 may be associated with a second tube, wherein the tubes are interconnected so that the material of the first Pipe can flow into the second pipe. For example, the first tube and the second tube may each have a screw conveyor 26. The Torrefizierungsvornchtung 14 may include, for example, two series-connected screw reactor. The first is z. B. for heating and the second provided for cooling.

Claims

1 method for producing a solid fuel from biomass, wherein biomass is fermented in a biogas plant (1), wherein fermentation residues and biogas arise, characterized in that at least a portion of the fermentation residues from the biogas plant (1 1) a reactor space (34) of a Torrefizierungsvorrichtung (14), where they are heated to exclusion of air and torrefied to produce a solid fuel.

2. Apparatus for producing a solid fuel from biomass, in particular for carrying out the method according to claim 1, with a biogas plant (1 1), by means of which fermentation residues and biogas can be generated and in the material flow direction of the biogas plant (11) downstream drying plant (13) Drying of fermentation residues of the biogas plant (1 1), characterized in that in the material flow direction behind the biogas plant (1 1) a Torrefizierungsvorrichtung (14) is arranged.

3. Apparatus according to claim 2, characterized in that a reactor space (34) of the Torrefizierungsvorrichtung (14) is associated with a heating device for heating the fermentation residues.

4. Apparatus according to claim 3, characterized in that the heating device comprises a reactor chamber (34) associated heating jacket (35, 39) for indirect heating of the reactor space (34) located digestate, and that the heating jacket of (35, 39) a hot fluid can flow through.

5. The device according to claim 4, characterized in that the heating device comprises a heating device and that the fluid can be heated by means of the heating device, wherein the heating device biogas from the biogas plant (11) can be fed to the combustion.

5

6. The device according to claim 5, characterized in that the biogas of the biogas plant (1 1) a combined heat and power plant (12) with internal combustion engine (20) can be fed to the combustion and that the heating device of the internal combustion engine (20) of the cogeneration plant (12) is formed ,

i o

/.Vorrichtung according to claim 5, characterized in that the heating device is formed by a gas burner.

8. The device according to claim 3, characterized in that the heating device comprises at least one electrically operated heating element, by means of which in the reactor space (34) located digestate are heated.

9. The device according to claim 8, characterized in that the biogas 20 of the biogas plant (11) a cogeneration plant (12) with internal combustion engine (20) can be fed to the combustion and that the heater electrical energy for operating the electric heating element of the cogeneration plant (12) can be fed.

10.Vorrichtung according to any one of claims 2 to 9, characterized in that the reactor space (34) has an input (29, 45) for filling with digestate and at least a first output (30, 46) for removing the solid Torrefizierten fermentation residues and at least a second output (31, 50) is provided for the escape of exhaust gases produced during Torrefizierung.

30

1 1 .Vorrichtung according to claim 10, characterized in that via the second output (31, 50) of the reactor chamber (34) exhaust gases are supplied to the gas burner for combustion.

12.Vorrichtung according to any one of claims 10 or 1 1, characterized in that via the second output (31, 50) of the reactor space (34) exhaust gases of the drying plant (13) can be fed.