DE102021108719A1 - Process and device for converting the chemical energy of a fuel into heat and electrical energy - Google Patents

Abstract

1. Method for converting chemical energy of a fuel into mechanical work, with at least one device for storing and/or releasing thermal energy., characterized by the following steps: i) compression of an oxygen-containing gas in a compressor (10) to a pressure Pa ,;ii) discharge of the compressed gas (24), with a flow rate Mc, into a first thermal energy storage and delivery device (16), whereby the temperature of the gas is raised to Tc;iii) gasification of the fuel in the gasifier (2nd ) under a pressure Pa and production of a product gas (5);iv) Combustion of the product gas (5) from the gasifier (2) in a combustion chamber (6) with an oxidant gas having a temperature Tc and a flow rate Mc consisting of a first means (16) for storing and discharging thermal energy;v) feeding the combustion products (8), at a temperature Tf and a flow rate Mf, into a gas turbine (9);vi ) expanding the combustion products in the gas turbine (9) to the pressure Pg, cooling the gas to a temperature Tg;vii) discharging the expanded combustion products (13), at a flow rate Mh, through a second thermal energy storage and release device (15), preferentially lowering the temperature further to Th.

Description

The invention relates to a method and devices for converting chemical energy from fuels. Fuels can be biomass, organic waste (e.g. industrial waste, household waste, household waste, processed waste such as RDF - "refuse derived fuel"...), or fossil fuels.

The chemical energy of the fuel is converted into mechanical work, electricity and useful heat, using a new type of process. The method according to the invention achieves a higher degree of efficiency than the previously known methods and at the same time leads to significantly lower investment costs by avoiding expensive and technologically demanding components such as high-temperature valves and recuperative high-temperature heat exchangers, and by more compact components for gasification and combustion.

State of the art:

Renewable energies, e.g. also waste, play an increasing and increasingly important role in the production of energy. Also important is their property that they are CO2 neutral, which means that they do not cause any further increase in the concentration of carbon dioxide.

Biomass, including waste materials, has a unique position among renewable energies. Like fossil and nuclear energy, it ensures a constant supply of energy.

Today, energy from biomass is obtained, for example, by burning it in a furnace under atmospheric pressure and dissipating the resulting heat into a steam boiler. The resulting water vapor drives a steam turbine at high temperature and pressure.

The disadvantage of this method is its low efficiency. It is not suitable for the smaller power plants required for biomass. In a plant that is relatively large for biomass, e.g. from 5 to 10 MW electrical output, the electrical efficiency (if no useful heat is generated) is no more than 25%.

In a new process (patent specification DE 10 039 246 C2 ) the disadvantages of the steam process for biomass power generation are eliminated by introducing a gas cycle with indirect combustion. In this case, combustion gases give off their heat alternately to a first and a second device for the accumulation of heat. The stored energy is then alternately added from the first and second devices to the compressed air from the compressor, which continues into the gas turbine and expands there, releasing mechanical work. In this way, a higher efficiency is achieved than with the steam process of a plant of the same capacity, and the amount of electricity produced is no longer dependent on the production of heat.

The solution in the patent DE 10 039 246 C2 patent, however, has the problem of requiring high temperature valves that allow the first and second heat storage devices to operate alternately. Due to their operating parameters, these high-temperature valves are technologically demanding and therefore expensive, and also cause additional losses and a reduction in efficiency in the water-cooled variant. Another disadvantage is the amount of fly ash that comes with the gaseous products of combustion in thermal storage devices. These devices retain most of the ash so that the operation and life of the gas turbine is not limited by excessive levels of particulate matter. For this reason, the devices mentioned must be cleaned regularly to remove dust that has settled.

In the pamphlets DE 10 2009 038 322 A1 and DE 10 2009 038 323 A1 the mentioned problem of solid particles is largely solved by replacing conventional biomass combustion with gasification of biomass and then combustion of the gas so produced. This reduces the amount of ash in the exhaust gases, and thus accumulation in the devices for heat storage. In addition, this reduction in the amount of solid particles allows the use of higher combustion temperatures, thereby further increasing the efficiency of power generation. The reduction in the amount of dust also has a positive effect on the service life of the turbine.

The disadvantage of using high-temperature valves is not eliminated with the method and the two patents. They increase the investment costs of the system and reduce the efficiency when the valves are cooled. Another problem is the length of the gas lines connecting the combustion chamber to the devices for heat storage, or these devices to the gas turbine. The gas temperature in these pipelines is over 1000°C, which requires good internal insulation and further increases the investment costs. Cause despite the good quality of insulation these pipes, due to their length, additional heat losses.

In the patent DE 10 2009 037 805 B3 the application of gas turbines with indirect biomass firing is proposed, introducing a classic recuperative heat exchanger instead of devices for heat storage. Since the conventional recuperative heat exchanger is limited in terms of maximum temperatures, the working medium is further heated to the turbine inlet temperature by direct combustion of the natural gas in an additional combustion chamber in order to achieve sufficiently high temperatures for efficient gas turbine operation. This avoids the problems with particulate emissions and the use of high temperature valves.

• - Schlechte Wärmeübertragung, d.h. die hohe Temperaturdifferenz zwischen zwei Gasströmen, der einen extrem schlechten Einfluss auf den Wirkungsgrad der Stromerzeugung hat (niedriges Niveau der Rekuperation des Gasturbinenprozesses);
• - Die Notwendigkeit hochwertige hitzebeständige Stähle zu verwenden (in der Patentschrift ist als Beispiel die Temperatur der erhitzten Druckluft von 750°C angegeben), die die Investitionskosten erhöhen;
• - Diese Wärmetauscher haben, trotz teuren Materialien, keine lange Lebensdauer, so dass sie nach einiger Zeit ersetzt werden müssen.

However, the gas-gas high-temperature heat exchanger has a number of disadvantages, such as:

• - Poor heat transfer, ie the high temperature difference between two gas streams, which has an extremely bad impact on the efficiency of power generation (low level of recuperation of the gas turbine process);
• - The need to use high-quality heat-resistant steels (the example given in the patent is the temperature of heated compressed air of 750°C), which increases investment costs;
• - Despite expensive materials, these heat exchangers do not have a long service life, so that they have to be replaced after some time.

In addition, there is a need for additional fuel, which must be a high-quality gas. When it comes to natural gas, the advantage of using renewable energy sources disappears.

In DE 1 040 320 A describes a regenerator in connection with a gas turbine plant. The regenerator, with the appropriate heat storage mass, serves as a "temperature rectifier" to ensure an even temperature of the propellant gas so that no dangerous temperature peaks occur on the turbine blading. This problem can also be solved, for example, by better pre-mixing of fuel and combustion air. An improvement in efficiency is not mentioned.

In the disclosure document DE 3 931 582 A1 describes the use of at least two regenerators in a method for using high-temperature heat using a gas turbine plant. However, the waste heat from the regenerator (380°C) or from the gas turbine outlet (490°C) is fed to a waste heat boiler and is no longer used for the gas process, which is why the efficiency of power generation remains low.

Several examples in the patent DE 4 317 947 C1 show the application of a high-temperature regenerator for the gas turbine cycle. However, the method proposed there requires expensive devices with several compression and relaxation stages. An expansion turbine for the fuel gas produced is also provided in the proposed fluidized-bed pressure gasification of lignite. This requires dedusting in an electrostatic precipitator. However, it is known that an electrostatic precipitator does not guarantee the dust-freedom required for reliable turbine operation.

aim of the invention

The aim of this invention is the conversion of chemical energy from fuels containing carbon and/or hydrogen through gasification and combustion into mechanical work, electricity and useful heat, while achieving a higher efficiency than the current state of the art. At the same time, the investment costs are significantly reduced by avoiding technically demanding and expensive components such as high-temperature valves and recuperative high-temperature heat exchangers, as well as more compact and cheaper components for gasification and combustion.

The object of the present invention is to create a method and a device for the conversion of chemical energy into mechanical work and further into electricity, in which the investment costs are lower and the efficiency higher than in the prior art.

This object is achieved with a method as defined in claim 1 and with the apparatus for pressurized gasification and combustion as defined in claim 9. Further design variants that provide advantages and improvements to the basic design are given in the respective subclaims.

The term gasifier is understood in particular to mean a counterflow gasifier which, by properly controlling the temperature, produces a product gas with a negligible content of fine dust, which is of the utmost importance for the proper and reliable operation of the gas turbine. Instead of the gasifier, a device for the pyrolysis of a fuel can be used. In this case, preference is given only the first and fastest stage of gasification and the product is not only the product gas, but also coke or charcoal.

The new process is particularly suitable for using biomass as a fuel, but any substances containing carbon or hydrogen can also be used. This can be, for example, waste biomass from agriculture or the food industry, the solid residue from the fermentation process, bark, stones from various fruits and the like. Industrial or municipal waste can be used, especially when given the right structure and granulation for the counterflow gasifier.

In this case it can be advantageous that the input material is first shredded or pelleted or briquetted. In addition, however, a large number of fossil fuels or very young fuels (which are therefore not considered fossil), such as peat, can also be used.

In a method according to the invention for converting chemical energy of a fuel into mechanical work, at least one device for storing and/or releasing thermal energy is provided.

1. i) Komprimierung eines sauerstoffhaltigen Gases, insbesondere in einem Kompressor auf einen Druck Pa;
2. ii) Abführen des verdichteten Gases (insbesondere mit einem ersten Durchfluss) in eine erste Einrichtung zur Speicherung und Abgabe thermischer Energie, wobei bevorzugt die Temperatur des Gases auf Tc erhöht wird;
3. iii) Vergasung des Brennstoffes im Vergaser unter einem Druck Pa und Erzeugung eines Produktgases das bevorzugt unter gleichem Druck Pa zur Verfügung steht;
4. iv) Verbrennung des Produktgases aus dem Vergaser in einer Brennkammer, insbesondere unter gleichem Druck Pa, mit einem Gas als Oxidationsmittel mit einer Temperatur Tc und bevorzugt einem Durchfluss Mc, der aus einer ersten Einrichtung zur Speicherung und Abgabe thermischer Energie zugeführt wird;
5. v) Zuführen der Verbrennungsprodukte, mit einer Temperatur Tf und einem Durchfluss Mf, in eine Gasturbine;
6. vi) Entspannung der Verbrennungsprodukte in der Gasturbine auf den Druck Pg, wobei das Gas auf eine Temperatur Tg abgekühlt wird;
7. vii) Abführen der entspannten Verbrennungsprodukte, mit einem Durchfluss Mh, durch eine zweite Einrichtung zur Speicherung und Abgabe thermischer Energie, wobei bevorzugt die Temperatur weiter auf Th gesenkt wird;

The following steps are envisaged:

1. i) compression of an oxygen-containing gas, in particular in a compressor, to a pressure Pa;
2. ii) discharging the compressed gas (particularly at a first flow rate) into a first thermal energy storage and release device, preferably wherein the temperature of the gas is raised to Tc;
3. iii) Gasification of the fuel in the gasifier under a pressure Pa and generation of a product gas which is preferably available under the same pressure Pa;
4. iv) Combustion of the gaseous product from the gasifier in a combustion chamber, in particular under the same pressure Pa, with a gas as oxidizing agent with a temperature Tc and preferably a flow rate Mc, which is supplied from a first thermal energy storage and release device;
5. v) feeding the products of combustion, at a temperature Tf and a flow rate Mf, into a gas turbine;
6. vi) expansion of the combustion products in the gas turbine to the pressure Pg, whereby the gas is cooled to a temperature Tg;
7. vii) discharging the flashed combustion products, at a flow rate Mh, through a second thermal energy storage and release means, preferably the temperature being further reduced to Th;

Preferably, the combustion products and in particular the cooled combustion products are then discharged. In this case, the combustion products can be released into the atmosphere, in particular through a chimney.

In a further advantageous method, the dwell time of the gases in the combustion chamber is more than 0.1 s, preferably more than 0.3 s and particularly preferably more than 0.5 s. The residence time of the gases in the combustion chamber is preferably less than 10 s.

In a further advantageous method, the compressed gas, in particular at the temperature Ta, is cooled in a cooler to a temperature Tb below 200°C, preferably below 150°C and particularly preferably below 90°C.

In a further preferred method, at least part of the compressed gas, in particular with a flow rate Md, is conducted into the pressure gasifier and is preferably used as a gasifying agent. In addition or in addition, the compressed gas, in particular with a flow rate Md, is fed into a device for increasing the proportion of water vapor.

In a further preferred method, at least part of the expanded combustion products, in particular with the flow rate Mj, is discharged through a recuperative heat exchanger, the temperature of which is preferably reduced to a value Tj that is close to temperature Th (and/or no more than 20%, preferably not more than 10% deviates from its temperature).

In a further advantageous method, a countercurrent gasifier and/or a device for the pyrolysis of the input fuel is used as the gasifier.

In a further advantageous method, the heat obtained in at least one of the heat exchangers is used to generate steam, with the steam produced preferably being used to further generate the mechanical work or electricity via a downstream steam turbine, ORC turbine or steam engine becomes.

In a further advantageous method, in at least one of the heat exchangers recovered heat used to produce useful heat.

In another preferred method, the input fuel is dried. The waste heat generated can be used for drying.

The waste heat from the combustion products of at least one of the branches Mh and Mj is particularly preferably used for drying the input fuel in a dryer.

The present invention is also directed to a device for converting the chemical energy of the fuel into mechanical work, this device having a gasifier and a combustion chamber as well as a compressor and a gas turbine. Furthermore, the device has a device for storing and/or discharging thermal energy and at least one line and in particular a pipeline that leads hot combustion products from the combustion chamber to the gas turbine.

According to the invention, the carburetor and the external combustion chamber are under a predetermined pressure Pa of less than 15 bar, preferably below 5 bar and particularly preferably below 3 bar, or the external combustion chamber and the carburetor are suitable for withstanding such pressures.

Furthermore, there is preferably no device for separating the particles between the carburetor and the external combustion chamber and/or the carburetor and the combustion chamber are preferably connected to one another directly (in particular via a line).

However, it would also be conceivable for a filter to be arranged between the gasifier and the combustion chamber, especially if the biomass used contains a large number of small particles (straw, spent grains, fermentation residues...), or if for some reason higher temperatures Te from the carburetor drives.

The device is preferably designed in such a way that the dwell time of the gases in the external combustion chamber is more than 0.5 seconds. This higher dwell time can be achieved by a higher pressure even if the dimensions of the combustion chamber are comparatively small.

In a preferred embodiment, the device has at least one heat exchanger and preferably at least two heat exchangers, which are used in particular for gas cooling. In this case, these heat exchangers can preferably be arranged downstream of the external combustion chamber and/or the carburetor, ie in particular in a direction of flow of gases downstream of the combustion chamber or of the carburetor.

In a further preferred embodiment, the device has a device for increasing the proportion of water vapor. In particular, the carburetor is preceded by a device for increasing the proportion of water vapor.

In a further preferred embodiment, the devices for storing and discharging thermal energy consist, at least in part, of substances or have substances that can absorb or bind possible harmful substances. Lime or activated carbon may be mentioned as examples of such substances.

In a further advantageous embodiment, the above-mentioned device for storing and/or releasing thermal energy has at least a first and a second device for storing and releasing thermal energy, which preferably alternately enters the branch at the outlet of the gas turbine and at the inlet are connected to the combustion chamber and/or a recuperative heat exchanger with a preferably continuous operation.

• 1 zeigt eine schematische Darstellung des Verfahrens gemäß der Erfindung.
• 2 zeigt ein Verfahrenschema gemäß der Erfindung, wobei das System eine weitere Abwärmenutzung zur Trocknung des Einsatzbrennstoffes beinhaltet;
• 3 zeigt eine weitere Darstellung des erfindungsgemäßen Verfahrens bzw. der erfindungsgemäßen Vorrichtung.

In a further preferred embodiment, the gas turbine is followed by a steam turbine, an ORC turbine or a steam engine. An additional bed is preferably present in the external combustion chamber, which acts as an integrated filter, so that the remaining minimal amount of fly ash is also removed from the gas flow. The patent application is described in detail with reference to the description and the 1 until 3 described.

• 1 shows a schematic representation of the method according to the invention.
• 2 shows a process scheme according to the invention, wherein the system includes a further use of waste heat for drying the input fuel;
• 3 shows a further representation of the method according to the invention and the device according to the invention.

• a) Verdichtung des sauerstoffhaltigen Gases auf einen Druck Pa (insbesondere durch einen Kompressor 10), wobei sich die Gastemperatur auf Ta erhöht;
• b) Abkühlen des komprimierten Gases auf Temperatur Tb;
• c) Ableitung des größeren Teils des verdichteten Gasstrom Mc in die erste Einrichtung 16 zur Speicherung und Abgabe thermischer Energie, wobei die Gastemperatur auf Tc steigt;
• d) Ableitung eines kleineren Teils des komprimierten Gasstromes Md in die Vorrichtung 26 für die Erhöhung des Wasserdampfanteils und anschließend in den Druckvergaser 2; Bevorzugt liegt der größere Teil des Gasstroms bei zwischen 60% und 95%, bevorzugt bei.
• e) Verbrennung des Produktgases aus dem Vergaser 2 in der Brennkammer 6, wobei als Oxidationsmittel das Gas aus der ersten Vorrichtung 16 zur Speicherung und Abgabe von Wärmeenergie, der Temperatur Tc und des Durchflusses Mc, dient;
• f) Abführung der Verbrennungsgase des Durchflusses Mf, mit der Temperatur Tf, in die Gasturbine 9;
• g) Entspannung der Verbrennungsgase in der Gasturbine auf Druck Pg (etwa gleich dem atmosphärischen Druck), wobei das Gas auf eine Temperatur Tg abgekühlt wird;
• h) Abführung des größten Teils der entspannten Verbrennungsprodukte Mh in die zweite Einrichtung 15 zur Speicherung und Abgabe thermischer Energie, wo sie weiter auf die Temperatur Th abgekühlt werden;
• j) Abführung eines kleineren Teils der entspannten Verbrennungsprodukte Mj in den rekuperativen Wärmetauscher 17, wo ihre Temperatur auf die Temperatur Tj, etwa gleich der Temperatur Th, gesenkt wird;
• k) Entlassung der gekühlten Verbrennungsprodukte, mit dem Durchfluss Mh und Mj, durch den Schornstein 19 in die Atmosphäre.

According to the in the 1 and 2 In the representations shown of the present invention for converting chemical energy into mechanical work and further into electricity, at least two devices for storage and release of thermal energy are used alternately, of which at least one is always connected to the outlet of the gas turbine, and the whole process the following steps includes:

• a) compression of the oxygen-containing gas to a pressure Pa (in particular by a compressor 10), the gas temperature increasing to Ta;
• b) cooling the compressed gas to temperature Tb;
• c) diverting the greater part of the compressed gas flow Mc into the first thermal energy storage and release device 16, with the gas temperature rising to Tc;
• d) discharge of a smaller part of the compressed gas flow Md into the device 26 for increasing the water vapor content and then into the pressure gasifier 2; Preferably the major part of the gas flow is between 60% and 95%, preferably at .
• e) Combustion of the product gas from the gasifier 2 in the combustion chamber 6, the oxidant being the gas from the first device 16 for storing and releasing thermal energy, the temperature Tc and the flow rate Mc;
• f) discharge of the combustion gases of flow Mf, at temperature Tf, into the gas turbine 9;
• g) expanding the combustion gases in the gas turbine to pressure Pg (approximately equal to atmospheric pressure), the gas being cooled to a temperature Tg;
• h) discharge of most of the expanded combustion products Mh to the second thermal energy storage and release device 15, where they are further cooled to the temperature Th;
• j) discharge of a smaller part of the expanded combustion products Mj into the recuperative heat exchanger 17, where their temperature is lowered to the temperature Tj, approximately equal to the temperature Th;
• k) discharge of the cooled combustion products, with flows Mh and Mj, through the chimney 19 into the atmosphere.

Preferably, the greater or major part of the expanded combustion products is between 60% and 95%.

Of the mechanical work that is obtained in the gas turbine in step g), part is used to drive the compressor 10 and the remainder to drive the generator G and thus to generate electricity. Depending on the operating parameters of the gas turbine, an electrical efficiency of over 37% can be achieved, which is well above the state of the art in this field.

The gas cooling in steps b) and j) can be used to obtain the useful thermal energy in the form of hot water and/or steam, so that the entire process and plant can be used for cogeneration. This achieves a utilization of the chemical energy yield of over 85%.

The following applies to the gas temperatures: Th <Ta <Tc <Tg <Tf. It is desirable that the temperature Th becomes lower than 150°C, preferably lower than 100°C. The temperature Tf is the highest in the system and its magnitude depends on the operating parameters of the gas turbine. If the temperature Te remains at a level below 140°C, the product gas from the gasifier will not contain any solid particles, which is an advantage of the invention. However, it is also possible to use a dust filter.

Air or a mixture of air and water vapor does not always have to be used as the oxidizing agent at the entrance to the carburetor or at the entrance to the combustion chamber. It can also be any other gas containing oxygen, such as a mixture of carbon dioxide (CO2) and oxygen.

At the compressor outlet, before or after the cooler, a small part of the air or oxygen-containing gas can be fed into the branch at the turbine inlet and used by means of a control valve to maintain a constant temperature Tf at the turbine inlet. In this way, the turbine output can also be controlled by controlling the turbine inlet temperature.

In cases where there is no heat consumption for the useful heat from the chiller in steps b) and/or j), this heat can be used for additional power generation, by downstream installation of a small steam turbine, steam engine, ORC turbine (Organic Rankin Cycle) , Stirling engine, or similar systems.

It is particularly advantageous not to direct the exhaust gases, with flows Mj and Mh, and temperatures Tj and Th, directly into the chimney 19, but to use them first for drying the fuel, in order to increase its calorific value, reduce fuel consumption and thus further improve the profitability of the plant. In this case it can be expedient to increase the temperatures Th and Tj due to lower heat dissipation in the recuperative gas cooler after the compressor or after the turbine.

1 Figure 1 shows a process diagram and the arrangement of the devices for the realization of the invention for the conversion of the chemical Fuel energy into mechanical work and further into electricity.

Fuel 1 enters the gasifier 2 from above, while the gasifying agent 3, which maintains the increased pressure Pa in the gasifier, enters from below. Ash, as the residual product of the gasification, leaves the gasifier through the system 4. The resulting product gas 5 is fed directly, i.e. without prior purification, to the combustion chamber 6, which is also under pressure, with combustion with oxygen-containing gas 7 at temperature Tc takes place.

The products of combustion 8, at temperature Tf, enter the gas turbine 9 where they expand and produce mechanical energy which is further used to drive the compressor 10 and electrical generator 11. Due to the expansion, the pressure reduces to Pg, which is close to atmospheric pressure, and the temperature falls to Tg.

Of the total combustion products 12, the largest part 13 (flow rate Mh) goes to the second thermal energy storage and release device 15, and the smaller part 14 (flow rate Mj) to the recuperative heat exchanger 17. In the device 15, the combustion products are Temperature Th cooled by releasing the heat to a bed, and conveyed with fan 18 through the chimney 19 into the atmosphere. In the recuperative heat exchanger 17, the combustion products are cooled to a temperature Tj, which in the optimum case is close to the temperature Th, and are discharged into the atmosphere by the fan 20 via a chimney 19. However, the fans 18 and 20 can also be dispensed with.

Compressor 10 compresses inlet air 21 (or other oxidant) to pressure Pa, raising temperature to Ta. Compressed gas 22 is cooled in a heat exchanger 23 to a temperature Tb and the major part 24 of the compressed gas stream Mc is diverted into the first thermal energy storage and release device 16 .

A small part 25 of the compressed gas stream Md is fed into the gasifier 2 . In the second device 16, the gas is heated to a temperature Tc by absorbing the heat stored in the bed, and is conducted further via the pipeline 7 into the combustion chamber 6. The rest of the gas 25 is humidified in a device 26 for increasing the proportion of water vapor before it reaches the gasifier 2.

Electrical energy is generated in the generator 11, with the waste heat from the heat exchangers 17 and 23 being able to be used for the production of useful heat, such as district heating, hot water, process steam or for other industrial processes.

2 shows another way of using the exhaust gas to dry the fuel, which reduces the specific fuel consumption and thus increases the efficiency of energy use.

The fans 18 and 20 do not direct exhaust gases directly into the chimney 19, but first into the fuel dryer 27. Thus, the temperature of the exhaust gases further decreases to Tk, and only then, through the chimney 19, the exhaust gases enter the atmosphere. On the other hand, due to the loss of water contained in the input fuel, or only a part of it, the calorific value of the fuel increases, which reduces the fuel consumption while the plant performance remains unchanged.

Bulk material regenerators can be used particularly advantageously as devices for storing and discharging thermal energy 15 and 16; DE4236619C2 or EP0620909B1 are known. The disclosure content of the aforementioned documents is hereby included. The use of such bulk material regenerators makes it possible to achieve particularly high efficiencies. Classic regenerators with an axial direction of flow can also be used, particularly in the case of low flow rates.

At least two devices for storing and releasing thermal energy, which are in alternating operation, are required for storing the heat from expanded combustion products at the turbine outlet and for dissipating heat to the compressed gas at the compressor outlet.

In order to allow alternating operation of the first and second devices for heat storage in the expanded products of combustion branch and in the compressed gas branch, respectively, at least one element, such as a valve for opening and closing the gas flow, is required in each branch . The highest operating temperature is Tg and thus much lower than the temperature of the gases at the turbine inlet Tf: Tg « Tf.

In order not to interrupt the gas flows during the alternating operation of the devices for heat storage, or a quasi-continuous To enable the process, it is advantageous to have at least three of the devices mentioned.

Instead of a bed of inert material such as aluminum oxide or gravel, other materials such as Eifel lava, lime, activated carbon or a catalyst can be used. This is another advantage of the proposed invention, especially when there are some products/chemicals present at the turbine exit that need to be sorted out before the gases are released into the atmosphere. This material may be in its natural form, such as grit or crushed stone, i.e. not necessarily in the form of regular spheres.

In a further preferred configuration of these devices for storing and discharging thermal energy, it is possible for the combustion products at the outlet of the turbine to be cooled to 150° C., preferably to 90° C., in less than 200 ms. Rapid cooling can prevent unwanted chemical reactions, such as B. a "de novo" -synthesis of dioxins and furans take place.

In exceptional cases, when the temperature at the turbine outlet is sufficiently low and a clean gas comes out, instead of the first and second thermal energy storage and delivery devices, a classic recuperative heat exchanger can be used so that the process runs continuously and the valves to open / close the Gas flow are not needed. This procedure is used in 3 described.

Preferably, the carburettor is under pressure Pa and thus a much smaller volume is required than with an atmospheric carburettor, which is an additional advantage of the invention. Reduction in volume, as well as investment costs, is approximately equal to the reciprocal of pressure Pa. On the other hand, there is a gas leakage prevention and pressure equalization system at the biomass inlet and the ash outlet.

The combustion chamber is also under pressure Pa, and therefore also has reduced dimensions. This also reduces the investment costs for the combustor, which is another advantage of the invention. On the other hand, the pressure increase allows for an extended burn time, so despite the compact size, the residence time is over 0.5s, better over 2s. A longer residence time in a fuel chamber provides for complete combustion of the product gas without risk of the exhaust gases containing hydrocarbons or carbon monoxide. Preferably, an additional bed is used at the combustion chamber exit, which acts as an integrated filter, so that the remaining minimum amount of dust/fly ash is also removed from the gas flow. This extends the life of the turbine.

3 shows a further embodiment of the method according to the invention. In this method, a (in particular recuperative) heat exchanger 28 is provided instead of the first and second device for storing and discharging thermal energy.

The greater part Mc of the compressed gas stream is fed to this heat exchanger 28 on one side. The larger part Mh of the expanded combustion products is fed to the heat exchanger on the other side.

The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided they are new compared to the prior art, either individually or in combination. It is also pointed out that the individual figures also describe features which can be advantageous in and of themselves. The person skilled in the art recognizes immediately that a specific feature described in a figure can also be advantageous without adopting further features from this figure. Furthermore, the person skilled in the art recognizes that advantages can also result from a combination of several features shown in individual figures or in different figures.

Reference List

1

Fuel entry into the carburetor

2

carburetor

3

Entry of the gasification agents

4

ash discharge

5

Escape of the product gas

6

combustion chamber

7

Combustion air / oxygen-containing gas

8th

combustion products

9

Gas turbine / expander

10

compressor

11

power generator

12

Relaxed combustion products

13

Part of the expanded combustion products for the second thermal energy storage and release facility

14

Part of the expanded combustion products for the recuperative heat exchanger

15

Second device for storing and discharging thermal energy

16

First facility for storing and discharging thermal energy

17

Recuperative heat exchanger

18

exhaust fan

19

Chimney

20

exhaust fan

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 10039246 C2 [0007, 0008]
• DE 102009038322 A1 [0009]
• DE 102009038323 A1 [0009]
• DE 102009037805 B3 [0011]
• DE 1040320 A [0014]
• DE 3931582 A1 [0015]
• DE 4317947 C1 [0016]
• DE 4236619 C2 [0063]
• EP 0620909 B1 [0063]

Claims (15)

Method for converting chemical energy of a fuel into mechanical work, with at least one device for storing and/or releasing thermal energy., characterized by the following steps: i) compression of an oxygen-containing gas in a compressor (10) to a pressure Pa,; ii) discharging the compressed gas (24), at a flow rate Mc, into a first thermal energy storage and release device (16), whereby the temperature of the gas is raised to Tc; iii) gasification of the fuel in the gasifier (2) under a pressure Pa and generation of a product gas (5); iv) Combustion of the product gas (5) from the gasifier (2) in a combustion chamber (6) with an oxidant gas having a temperature Tc and a flow rate Mc supplied from a first thermal energy storage and release means (16). ; v) feeding the combustion products (8), at a temperature Tf and a flow rate Mf, into a gas turbine (9); vi) expansion of the combustion products in the gas turbine (9) to the pressure Pg, the gas being cooled to a temperature Tg; vii) discharging the expanded combustion products (13), at a flow rate Mh, through a second thermal energy storage and release device (15), preferably with the temperature being further reduced to Th. procedure after claim 1 , characterized in that the residence time of the gases in the combustion chamber (6) is more than 0.5 seconds. Method according to at least one of the preceding claims, characterized in that the compressed gas (22) at the temperature Ta is cooled in a cooler (23) to a temperature Tb. Method according to at least one of the preceding claims, characterized in that a part of the compressed gas (25) with a flow rate Md, in the pressure gasifier (2) and used as a gasification agent and / or the compressed gas (25) with a Flow Md, in a device for increasing the proportion of water vapor (26) is passed. Process according to at least one of the preceding claims, characterized in that part of the expanded combustion products (14), with flow rate Mj, is discharged through a recuperative heat exchanger (17), the temperature of which is reduced to a value Tj close to temperature Th lies, is lowered. Method according to at least one of the preceding claims, characterized in that a countercurrent gasifier or a device for the pyrolysis of the input fuel is used as the gasifier (2). Method according to at least one of the preceding claims, characterized in that the heat obtained in at least one of the heat exchangers (17) and (23) is used to generate steam, with the steam generated preferably being used to further generate the mechanical work or the current, via a downstream steam turbine, an ORC turbine or a steam engine. Method according to at least one of the preceding claims, characterized in that the heat obtained in at least one of the heat exchangers (17) and (23) is used to produce useful heat and/or the waste heat from the combustion products, from at least one of the branches Mh and Mj, is used for drying the input fuel in a dryer (27). Device for converting the chemical energy of the fuel into mechanical work, comprising: a gasifier (2) and a combustion chamber (6); a compressor (10) and a gas turbine (9); a device for storing and/or discharging thermal energy, and at least one pipeline which leads hot combustion products from the combustion chamber (6) to the gas turbine (9) , characterized in that - the gasifier (2) and the external combustion chamber (6) are under pressure Pa, - the residence time of the gases in the external combustion chamber (6) is preferably more than 0.5 seconds. device after claim 9 , characterized in that heat exchangers (17) and (23) are connected downstream for gas cooling. device after claim 9 or 10 , characterized in that the carburettor (2) is preceded by a device for increasing the proportion of water vapor (26). Device according to at least one of the preceding claims 9 - 11 , characterized in that the means (15) and (16) for storing and discharging thermal energy consist, at least in part, of substances such as lime or activated charcoal, which can absorb or bind possible harmful substances. Device according to at least one of the preceding claims 9 - 12 , characterized in that the device for storing and/or releasing thermal energy comprises at least a first (16) and a second (15) device for storing and releasing thermal energy which are alternately fed into the branch at the outlet of the gas turbine (9), or at the entrance to the combustion chamber (6) are connected or is a recuperative heat exchanger with continuous operation. Device according to at least one of claims 9 - 13 , characterized in that the gas turbine (9) is followed by a steam turbine, an ORC turbine or a steam engine. Device according to at least one of claims 9 - 14 , characterized in that in the external combustion chamber (6) there is an additional bed, which acts as an integrated filter, so that the residual minimum amount of fly ash is also removed from the gas flow.

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