EP2403927A2

EP2403927A2 - Method and device for utilizing biomass in a biomass gasification process

Info

Publication number: EP2403927A2
Application number: EP10707267A
Authority: EP
Inventors: Helmut Kammerloher; Sven Johannssen; Van Cung Tran
Original assignee: Krones AG
Current assignee: Krones AG
Priority date: 2009-03-05
Filing date: 2010-03-03
Publication date: 2012-01-11
Also published as: CN102361962A; DE102009011358A1; WO2010100174A2; WO2010100174A3; US20120017497A1; EA021911B1; GEP20146097B; UA105924C2; EA201190154A1

Abstract

The invention relates to a method for utilizing biomass, wherein the following steps are performed: First, at least one raw material containing carbon is thermally gasified. In a next step, the synthesis gas produced in the gasification is purified. During said purification, the temperature of the synthesis gas is changed. Then the synthesis gas is preferably converted into a liquid fuel by means of a catalyzed chemical reaction, wherein a straw-like biomass is selected as the raw material containing carbon, the gasification is performed in a fixed bed reactor, and the ash-softening temperature of the straw-like raw material is increased by adding at least one alkaline-earth salt.

Description

Method and apparatus for utilizing biomass in a biomass

gasification process

description

The invention relates to a method and an apparatus for utilizing biomass in a (thermal) biomass gasification process according to the preambles of claims 1, 9 and 10 and in particular to a method for increasing the ash softening point of stalk-like biomass.

The invention is related to the production of BtL fuels (biomass to liquid). This term refers to fuels that are synthesized from biomass. In contrast to biodiesel BtL fuel is generally obtained from solid biomass, such as firewood, straw, biowaste, animal meal or reeds, ie made of cellulose or hemicellulose and not only from vegetable oil or oil crops.

The great advantages of this synthetic biofuel are its high biomass and area yields, which are up to 4000 l per hectare, without any competition for food. In addition, this fuel has a high CO ₂ -

Mitigation potential of over 90% and its high quality is not subject to any restrictions in today's and foreseeable engine generations.

Usually, in the production of BtL fuels in a first process step, a gasification of biomass is carried out and a subsequent generation of synthesis gas. This is at elevated pressure and elevated temperature to the liquid Fuel synthesized.

Due to the rising prices for wood fuels, pulp-like biomass, for example grain straw, rape straw or meadow hay, is becoming increasingly important as a fuel. However, straw has significantly different properties in the combustion process or gasification process than, for example, wood.

Various carburettors are also known from the prior art, such as autothermal fixed-bed gasifiers or autothermal air flow gasifiers (see SunDiesel - made by Choren - Experiences and Latest Developments, Matthias Rudioff in "Synthetic Biofuels", volume "Renewable Resources" Volume 25) , Agricultural Publishing GmbH, Münster 2005).

For example, fluidized bed gasifiers according to the "Güssing principle" are known from the prior art. The necessary gasification energy is applied by supplying hot sand (at a temperature of 950 ^° C.). The preheating of this sand is in turn generated by the combustion of raw material used (in this case, biomass). Thus, the valuable raw material is used as an energy source, which reduces the specific yield.

Furthermore, according to EP 1 837 390 A1, the treatment of biological fuel, in particular Roholz, by the addition of burnt lime known, using the hygroscopic effect of quicklime, an improved degree of drying of the raw materials to be achieved. The processed kiln is processed after mixing with quicklime to solid fittings.

DE 198 36 428 C2 describes methods and devices for gasification of biomass, in particular of wood pulp. In this case, a fixed-bed gasification in a first gasification stage is effected at temperatures up to 600 ⁰ C and in a subsequent second gasification stage a fluidized bed gasification at temperatures between 800 ⁰ C and 1000 ⁰ C.

From DE 10 2005 006305 A1 a method for the production of combustion and synthesis gases with high-pressure steam generation is known. In this process, gasification processes are used in an air flow gasifier at temperatures below 1200 ⁰ C. Due to the high chloride and potassium content of the ash softening point of cereal straw is about 800 ⁰ C, well below the wood with about 1200 ⁰ C. The disadvantage this results in that greater than about 800 ° C, the ash herbaceous biomass soft in a at reactor temperatures , Pasty slag passes, which leads to clumping in the reactor.

The present invention is therefore an object of the invention to provide a method and an apparatus for the efficient gasification of coal-containing raw materials, especially halmgutartigen raw materials available, which allows gasification of the raw material at higher temperatures and in particular avoids clumping of the biomass.

In addition, the device according to the invention should also be suitable overall for smaller capacities and a possible decentralized operation with different starting materials in order to achieve good economy and to be usable for allothermal as well as for autothermal gasification.

This is achieved by a method according to claim 1 and an apparatus according to claim 9. Advantageous embodiments and further developments are the subject of the subclaims.

In a method according to the invention for increasing the ash softening point of carbonaceous raw materials, the following steps are carried out: First, the thermal gasification of at least one carbonaceous raw material is carried out. In a next step, the purification of the gas formed during the gasification takes place. In this case, a temperature change of the synthesis gas is made.

According to the invention a halmgutartige biomass is selected as the carbonaceous raw material, the gasification preferably carried out in a fixed bed reactor and the ash softening point of the halmgutartigen raw material increased by the addition of at least one alkaline earth metal salt. Under a halmgutartigen raw material is understood in particular a raw material, which is selected from a group of raw materials containing grasses, straw, hay, reeds, rape straw, cereal straw combinations thereof or the like.

As a result of the combination according to the invention of the use of a fixed bed reactor for the stalk-type biomass and the addition of the alkaline-earth salt, special synergy effects can be achieved, as could be shown in extensive investigations. A fixed bed reactor has the advantage that it can be flowed through both from above and from below. In addition, in the case of a fixed bed reactor, product discharge is relatively easy. In this case, the discharge of the ash is considerably simplified by the mentioned increase in the ash softening point.

Preferably, then, i. especially after the temperature change of the synthesis gas, the conversion of the synthesis gas into a liquid fuel by means of a catalyzed chemical reaction.

The alkaline earth metal salt is preferably selected from the group consisting of calcium and / or magnesium and also carbonate, hydroxide, bicarbonate and / or oxide.

Particularly preferred is the alkaline earth metal salt in the form of calcined (CaO) and / or slaked lime (Ca (OH) ₂ and / or calcium carbonate (CaCO ₃ ) and / or calcium hydrogen carbonate (Ca (HCO ₃ ) ₂ during, if necessary, before It is also possible to use mixtures of these substances The amount of alkaline earth metal salt added is preferably 0.1-10.0% by weight, preferably 1.0-3.0% by weight, based on the Total mass of stalk-like raw material and alkaline earth salt (s).

Preferably, the alkaline earth salt is added in the form of dolomite and / or limestone during, possibly also before the thermal gasification. In particular, the working temperature in the gasifier is maintained above the ash melting point of the stalk-like raw material.

Preferably, the ash softening point of the pulp-like raw material is lower than that selected from wood or lower, wherein the ash softening point of the stalk-like Raw material before addition of the alkaline earth metal salt in a range of 600 ⁰ C to 1000 °, preferably in a range of 700 ⁰ C to 900 ⁰ C, more preferably at about 800 ⁰ C is set.

Advantageously, the waste heat from at least one gasification-following process is used for saturated steam production.

The present invention is further directed to processes for the utilization of carbonaceous raw materials, wherein a thermal gasification of at least one carbonaceous raw material takes place. According to the invention a halmgutartige biomass is selected as a carbonaceous raw material, the gasification carried out in a fixed bed reactor and the ash softening point of the halmgutartigen raw material increased by the addition of at least one alkaline earth metal salt. Preferably, the process is carried out in the manner described above.

A device according to the invention for converting carbonaceous raw materials, in particular of biomass into liquid fuels or usable gases, includes a gasifier in which the carbonaceous raw materials are gasified, at least one cleaning unit for purifying the synthesis gas produced during the gasification, at least one temperature change unit Changing the temperature of the resulting synthesis gas and preferably a conversion unit for converting the synthesis gas into a liquid fuel, wherein the carbonaceous raw material comprises at least one halmgutartigen raw material whose ash softening point is increased by the addition of at least one alkaline earth metal salt.

Preferably, the gasifier is a fixed bed reactor.

In particular, the ashes of the stalk-like raw material is continuously removable from the fixed bed tractor. Preferably, the device has a feed device which supplies the alkaline earth salt to the raw material. This feeding device advantageously allows a metered addition of the alkaline earth metal salt to the raw material or the biomass, wherein a continuous addition during a current gasification process is possible.

In addition, the gasification of the stalk-like raw material in the fixed bed tractor is both lothermic as well as autothermal feasible.

Thus, the method according to the invention is divided into at least three process steps, wherein initially, for example, an allothermic gasification of the raw material such as biomass and in particular straw or cereal straw and / or rape straw, for example, with water vapor, which serves as a gasification agent and energy source is made. In the subsequent cleaning process, a purification of the gas, in particular of dust and tar, and preferably a subsequent recycling of these substances in the gasification process is carried out. For example, in the context of a Fischer-Tropsch synthesis, synthesis gas is converted into liquid fuels.

In order to achieve complete gasification, it is necessary that the steam used has a temperature which is well above the average gasification temperature. Therefore, temperatures of at least 1000 ⁰ C are used, but preferably temperatures of more than 1200 ⁰ C.

By means of the recuperative heat exchangers used in the prior art, it has hitherto not been possible to achieve such steam temperatures. However, bulk generators can be used, as described for example in EP 0 620 909 B1 or DE 42 36 619 C2. The disclosure of EP 0 620 909 B1 and DE 4 236 619 C2 are hereby incorporated by reference in their entirety into the disclosure herein. The use of such bulk regenerators leads to a device which is more efficient than the prior art.

In a further preferred method, the highest temperature within the carburetor is always above the ash melting point of the raw material. In this way it can be achieved that ash is discharged in the liquid state.

The gasifier is preferably a fixed bed countercurrent gasifier. In principle, various types of carburettors according to the prior art can be used. However, the particular advantage of a countercurrent fixed bed gasifier is that within this reactor individual zones are formed in which different temperatures and thus different processes occur. The different temperatures are based on the fact that the respective processes are strongly endothermic and the heat only from below comes. In this way, the very high steam temperatures are utilized in a particularly advantageous manner. Since the highest steam temperatures prevail in the entry zone of the gasification agent, it is possible to always produce the conditions for a liquid ash discharge.

This is particularly advantageous in biomass gasification because there the ash melting points deviate very much depending on the fuel grade and the soil properties.

In the prior art, it has hitherto not been possible to convert different fuels with a particular type of carburettor and thus to adapt to the market situation. Due to the high temperatures, however, it is fundamentally possible according to the invention to design the process so that the resulting ash is always discharged in liquid form. In cases where the ash melting point is particularly high, a predetermined amount of flux may preferably be added to the fuel. By the above-described simultaneous supply of oxygen or air, a further increase in temperature in the ash discharge zone can be achieved.

The waste heat from at least one gasification-following process is preferably used for saturated steam generation. It is for example possible to use the waste heat from the described gas cooler for the preheating of the water for the saturated steam generation. Furthermore, the heat generated in the Fischer-Tropsch reactor itself waste heat can be used for the production of saturated steam. The exothermic synthesis reaction in the Fischer-Tropsch reactor requires constant and uniform cooling. The cooling is preferably carried out with boiling water and subsequent saturated steam generation.

Further advantages and embodiments will become apparent from the attached drawing:

It shows:

Fig. 1 is a schematic representation of a device according to the invention; and

Fig. 2 is a schematic illustration of a method according to the invention. 1 shows a schematic representation of a device 35 for converting carbonaceous raw materials into synthesis gas and for subsequent liquid fuel synthesis. It should be understood, however, that the apparatus shown in FIG. 1 is exemplary only and the present invention is also applicable to other equipment having a carburettor.

In this case, the reference numeral 1 refers to a fixed bed countercurrent reactor. The raw material 2 is introduced from above into the reactor 1 and the gasification agent 3 along a feed line 42 from below. In this way it is achieved that the gasification agent 3 and the synthesis gas produced flow through the reaction space in the opposite direction to the fuel flow. The resulting ash in the carburetor 1 is discharged downwards, that is, along the arrow P2.

Starting from the reactor 1, the synthesis gas passes via a line 44 into a Zyk- ion or preferably a multi-cyclone. In this cyclone 4 a large part of the tar and the resulting dust is eliminated and injected with a pump 5 back into the high temperature zone of the carburetor 1. The pre-cleaned in this manner the synthesis gas in which Restteer is present together with residual quantities of dust passes via a further conduit 46 into a thermal cracker 6. In this thermal cracker Restteer with the amount of dust at maximum temperatures between 800 ⁰ is C and 1400 ⁰ C destroyed. Optionally, in order to obtain the necessary temperature, a predetermined amount of oxygen and / or air can be injected directly into the high-temperature zone and in this way a partial oxidation of the tars can be achieved (see arrow P1).

After the thermal cracker, the synthesis gas passes via a line 48 into a gas cooler 7. In this gas cooler, the synthesis gas is cooled so far that 8 excess water vapor is condensed out in the downstream condenser. Optionally, the amount of CO ₂ in the synthesis gas can be reduced by means of a CO ₂ scrubber 9 or a PSAA / SA plant with molecular sieve technology. In addition, residual amounts of pollutants (which are in the ppm range) completely, for example by means of a

(not shown) scrubber with ZnO be removed. The reference numeral 10 refers to a gas preheater in which the synthesis gas is preheated to a suitable temperature for the subsequent Fischer-Tropsch synthesis taking place. The reference numeral 1 1 refers to a Fischer-Tropsch reactor in which from the synthesis gas under suitable thermodynamic conditions, that is, under appropriate pressure and temperature of the synthetic liquid fuel 12, z. B. BtL is generated in the case of biomass gasification. Saturated vapor 14 is formed as by-products of this synthesis by cooling the reactor 13 and an off-gas 15, which consists of unreacted synthesis gas and gaseous synthesis products. In addition, there is also a water condensate 16. This water condensate 16 can be drained via a valve 52.

The saturated steam 14 then passes through a connecting line 50, which is split into two sub-lines 50a and 50b, in two bulk regenerators 17 and 18. In these bulk regenerators, the water vapor is superheated to the required temperature. In the apparatus shown in Fig. 1, two bulk regenerators 17, 18 are provided which allow continuous operation of the system. While in the bulk regenerator 17, the water vapor is superheated, the bulk material regenerator 18 is in a heating phase, that is, it is here in particular by the combustion of off-gas 15, which is fed to it via a connecting line 54 from the Fischer-Tropsch reactor 1 1 , charged with heat energy. To control the two bulk regenerators, a plurality of valves 62 to 69 is used. The valves 62, 63, 66 and 68 are assigned to the bulk material regenerator 17 and the valves 64, 65, 67 and 69 to the bulk material regenerator 18.

The respectively resulting combustion gases leave the plant through a chimney 19. By the periodic switching of the valves 62-69 shown, the two bulk material regenerators 17 and 18 can be operated alternately. It is also possible to generate the necessary steam from the condensate, which originates from the condenser 8. Depending on the water content of the raw material 2, it is possible to use additional amounts of water, for example the condensate 16 from the Fischer-Tropsch reactor. Since the required amount of water is conveyed through the gas cooler 7 with the aid of the pump 20, preheating also takes place in this respect.

In the cooler 13 of the Fischer-Tropsch generator 1 1 saturated steam 14 is also generated, which in turn is overheated in the bulk regenerators 17 and 18, in which case the chemical energy from the off-gas 15 can be used. In this way, the superheated steam 3 supplied to the entire energy generated during the process waste energy and so the water vapor can be heated particularly advantageous.

Instead of the two bulk material regenerators 17, 18 shown in FIG. 1, it is also possible to use three or more bulk material regenerators in order to achieve particularly uniform operation.

Fig. 2 shows a schematic representation to illustrate the method according to the invention. Here, a fixed bed reactor both the stalk-like biomass (arrow A) is supplied as well as the above-mentioned alkaline earth metal salt (arrow B). The supply of the alkaline earth salt can take place both before and during the feeding of the biomass. Furthermore, it would be possible that the alkaline earth salt is mixed or mixed within the reactor 1 with the biomass. The resulting gas is removed from the reactor 1 (arrow C) and also the ash resulting from the gasification is discharged from the reactor 1 (arrow D).

All disclosed in the application documents features are claimed as essential to the invention, provided they are new individually or in combination over the prior art.

LIST OF REFERENCE NUMBERS

1 fixed bed - countercurrent - reactor

2 raw material

3 steam

4 cyclone

5 pump

6 crackers

7 gas coolers

8 capacitor

9 CO ₂ scrubbers

10 gas preheaters

1 1 Fischer-Tropsch reactor

12 liquid fuel 13 coolers

14 saturated steam

15 exhaust gas (off-gas)

16 condensate

17, 18 bulk regenerators

19 fireplace

20 pump

21 hot gas control valve

22 bypass line

23, 25 control valve

24 heat consumers

30 line

35 device

42 supply line

44, 46, 48 pipe

50a, 50b sublines

52 valve

54 connection line

62 - 69 valves

P1, P2, P3 arrows

A, B, C, D arrows

Claims

Method and device for the utilization of biomass in a biomass gasification process Patent claims

1. Process for recycling carbonaceous raw materials with the steps:

- thermal gasification of at least one carbonaceous raw material; - Purification of the gas produced during the gasification syngas;

- Temperature change of the synthesis gas d a d u rch zeken n ze i ch n et, d as the carbonaceous raw material a stalk-like biomass is selected, the gasification is carried out in a fixed bed reactor and the ash softening point of the halmgutartigen raw material is increased by the addition of at least one alkaline earth metal salt.

2. The method according to claim 1, characterized in that the alkaline earth metal salt is selected from the group consisting of calcium and / or

Magnesium and carbonate, hydroxide, bicarbonate and / or oxide and mixtures thereof.

3. The process according to claim 1, wherein the conversion of the synthesis gas into a liquid fuel takes place by means of a catalyzed chemical reaction.

4. Method according to at least one of the preceding claims, characterized in that the alkaline earth metal salt is in the form of calcined (CaO) and / or slaked lime (Ca (OH) ₂ and / or calcium carbonate (CaCO ₃ ) and / or calcium bicarbonate (Ca (HCO ₃ ) _{2 is added} during the thermal gasification.

5. Method according to at least one of the preceding claims, characterized in that the alkaline earth salt is added in the form of dolomite and / or limestone during the thermal gasification.

6. Method according to at least one of the preceding claims, characterized in that the working temperature in the gasifier (1) is kept above the ash melting point of the stalk-like raw material.

7. Method according to at least one of the preceding claims, characterized in that the ash softening point of the stalk-like raw material is lower than that of wood.

8. The method according to at least one of the preceding claims, dadu rch geken n i ze et ch n, d ass the ash softening point of the solid agro raw material before adding the alkaline earth metal salt in a range of 600 ⁰ C to 1000 °, preferably in a range of 700 ⁰ C. to 900 ⁰ C, more preferably at about 800 ° C.

9. Method according to at least one of the preceding claims, characterized in that the waste heat from at least one of the processes following the gasification is used for saturated steam production.

10. A process for the recovery of carbonaceous raw materials wherein a thermal gasification of at least one carbonaceous raw material takes place; Thus, as a carbonaceous raw material, a stalk-like biomass is selected, the gasification is carried out in a fixed bed reactor and the ash softening point of the stalk-like raw material is increased by the addition of at least one alkaline earth salt.

11. An apparatus (35) for converting carbonaceous raw materials and in particular biomass into liquid fuels, comprising a gasifier (1) in which the carbonaceous raw materials are gasified, at least one cleaning unit (4, 6) for purifying the synthesis gas produced during the gasification, at least one temperature change unit (7, 8, 10) for changing the temperature of the resulting

Synthesis gas and a conversion unit (11) for the conversion of the synthesis gas into a liquid fuel, d a d u rch zeken n ze ch ch et et, that the carbonaceous raw material comprises at least one halmgutartigen raw material whose ash softening point is increased by the addition of at least one alkaline earth metal salt.

12. Device (35) according to claim 11, characterized in that the gasifier (1) is a fixed bed reactor (1).

13. Device (35) according to at least one of the preceding claims 11-12, characterized in that the ash of the raw material of the stalk-type material is continuously removable from the fixed-bed reactor (1).

14. Device (35) according to at least one of the preceding claims 11-12, characterized in that the gasification of the pulp-like raw material in the fixed bed reactor (1) can be carried out both alloothermally and autothermally.