WO2016000850A1

WO2016000850A1 - Structure of an integrated power plant for operation with formic acid and operation of an integrated power plant with formic acid

Info

Publication number: WO2016000850A1
Application number: PCT/EP2015/059834
Authority: WO
Inventors: Manfred Baldauf; Uwe Lenk; Alexander Tremel
Original assignee: Siemens Aktiengesellschaft
Priority date: 2014-07-04
Filing date: 2015-05-05
Publication date: 2016-01-07
Also published as: EP3148926A1; DE102014212996A1

Abstract

The invention relates to a method for operating an integrated power plant with formic acid, comprising several steps. First, formic acid is produced catalytically from a solid fuel at low temperatures in a first reactor. Subsequently, the formic acid is decomposed to a mixture of hydrogen, carbon dioxide, carbon monoxide and/or water in a second and/or third reactor. This gas mixture is guided as fuel gas into a gas turbine, into an internal combustion engine or a fuel cell to generate current. The invention further relates to an integrated power plant for operation with formic acid.

Description

description

Development of an integrated power plant for operation with formic acid and operation of an integrated power plant with formic acid

The invention relates to a method for operating an integrated power plant with formic acid and an integrated power plant.

Conventional power plants are operated in particular with fossil fuels such as hard coal or lignite. The efficiency of these power plants is less than 46%. They are disadvantageously severely limited in terms of their fuel. Furthermore, they can only be operated with very low load flexibility. Even unconventional fuels, such as biomass as energy source in power plants, lead only to low efficiencies of less than 40%. Disadvantageously, these unconventional fuels often have a high water content or high Spurstoffbelastungen, especially sulfur and chlorine which leads to the firing areas of the power plants to versatile difficulties. Again, the load flexibility is very low. In integrated gasification power plants, a significant

Increased efficiency can be achieved. Efficiencies in the range of 60% are achieved in conventional gas and steam power plants (GUD). In an integrated gasification power plant, the solid fuel is typically first passed to a thermal gasifier and syngas generated.

This synthesis gas can be fed to a gas turbine with a downstream steam cycle, which then leads to higher efficiencies. In addition to the increased efficiency, the power plant can be operated with a higher load flexibility. However, in this power plant concept, the carburetor and the gas turbine are directly coupled with each other, so that the carburetor determines the load flexibility as the main factor and adversely restricts. A caching The synthesis gas is technically difficult because it requires extremely large storage volumes. Furthermore, wet fuels, such as wet biomass or lignite coal have the disadvantage that a predrying is necessary or the efficiency of the gasification and thus the total power plant drops sharply.

It is therefore an object of the invention to provide an integrated power plant and a method for operating an integrated power plant, which overcomes the disadvantages mentioned and can be operated with high load flexibility.

The object is achieved with a method having the features of claim 1 and with an integrated power plant having the features of claim 13.

The inventive method for operating an integrated power plant with formic acid comprises several steps. First, the catalytic production of formic acid from a solid fuel takes place at low temperatures in a first reactor. Subsequently, the decomposition of formic acid to a first mixture comprising hydrogen and carbon dioxide takes place in a second reactor. Parallel or alternatively, the decomposition of formic acid to carbon monoxide and water takes place in a third reactor. The gas mixtures are fed as fuel gas into a working machine for generating electricity.

The integrated power plant according to the invention for operation with formic acid from a solid fuel comprises a first reactor for the catalytic production of formic acid from the solid fuel at low temperatures. Furthermore, it comprises a second reactor for decomposing the formic acid to a first gas mixture comprising hydrogen and carbon dioxide. It additionally or alternatively comprises a third reactor for decomposing formic acid to a second gas mixture comprising carbon monoxide and water. It further comprises a working machine for generating electricity with the aid of the first and / or second gas mixture. The decomposition of the formic acid into a first gas mixture of hydrogen and carbon dioxide in the second reactor and the decomposition of the formic acid into carbon monoxide and water in the third reactor take place via two different decomposition reactions. The particular decomposition reaction can be controlled by choice of a suitable catalyst and the choice of reaction conditions. In the case of the reaction of formic acid to carbon monoxide and water, the water can be separated by condensation. Advantageously, a parallel guidance of these two reactions in the second and third reactor can be carried out. Subsequently, a gas mixture of the components hydrogen, carbon dioxide, carbon monoxide and water can be produced with a variable composition. The properties of the

Gas mixture can be advantageously adapted to the requirements of later use. The integrated power plant according to the invention and the method for operating this power plant thus advantageously make it possible to generate electricity with high load flexibility.

In an advantageous development of the invention, steam is generated or heated by means of the waste heat of the working machine and / or by means of the waste heat of the first reactor. Typically, a steam cycle is operated with this steam.

In a further advantageous embodiment of the invention, the steam is fed into a steam turbine for generating electricity.

The use of the waste heat of the working machine for a steam process advantageously increases the efficiency of the integrated power plant.

In an advantageous development of the invention, the formic acid is produced by means of a polyoxometalate catalyst. The catalyst has the form H _{3 + y} [PMo _x V _y 0 ₄ o], where for l <y <13, in particular 6 <y <13, -1 <χ <11, in particular - l <x <6, and x + y = 12. X and y represent whole numbers here. With the aid of this catalyst, it is possible to prepare not only formic acid but also other carboxylic acids. The method is particularly suitable for producing carboxylic acids from carbonaceous solid fuels, in particular from solid fossil fuels such as peat, lignite and hard coal, but also from renewable raw materials, such as woody biomass or moist biomass. In addition to woody biomass, green waste, algae or residues such as sewage sludge or black liquor and fiber sludge from the paper industry can also be used as fuels.

All fuels are first brought into solution. In this case, different solvents are used, in particular organics, ionic liquids, carbon dioxide or water. When using water as a solvent, additives are typically used to increase the solubility of the solid fuels. As an alternative to dissolving the solid fuel, an extraction of the solid fuel can also take place. During the extraction, defined substances are released from the solid fuel and pass into the aqueous phase of the solution. Another way to spend the solid fuel in solution may also be a grinding of the solid fuel. The solid fuel is then dissolved in suspension. In this case, the solid fuel is finely dispersed with a high surface area. After these alternative solution steps, the dissolved solids content is between 0.5 and 40 percent by weight in solution. Another way to solve the solid fuel is the dissolution of the solid fuel in supercritical C0 ₂ .

As the next step, the solution containing the solid fuel is added with the polyoxometalate catalyst of the form H _{3 + y} [PMo _x V _y 0 ₄ o]. The catalyst may be in an oxidized or reduced form. In its oxidized form, it converts dissolved solid fuel to carboxylic acids, especially to formic acid and acetic acid. In addition to formic acid and Es- Acetic acid also produces water and gaseous components. The main component of the gaseous phase is C02. During this reaction, the catalyst itself is reduced and is then present in its reduced form. In the presence of molecular oxygen, the catalyst is then regenerated to be in its oxidized form again. The oxygen partial pressure of the added gas for the regeneration of the catalyst is 0.1 bar up to 100 bar. This gas may be air, oxygen enriched or depleted air, or pure oxygen. The regeneration ie oxidation of the catalyst can take place in the same reaction vessel as the reduction or in a second reaction vessel. By continuous addition of oxygen and continuous reduction and oxidation of the catalyst, a continuous production of carboxylic acid can take place. The temperatures of the reaction are between 20 ° C and 150 ° C, in particular between 60 ° C and 95 ° C. The overall reaction is exothermic so that heat is ideally removed from the reactor. It is also conceivable that the solution step of the solid fuel and the reaction step are carried out integrated into carboxylic acids. The solid fuel and the corresponding additive are added directly to the reactor. The conversion of the solid fuel to formic acid or

Carboxylic acid can be carried out batchwise or continuously. In batch mode, the reaction time is from 5 minutes to 72 hours. In continuous operation, these times correspond to the mean residence time of the components in the reaction vessel. The reaction preferably takes place in continuous operation. Advantageously, after the reaction, the reaction mixture is fed to a filter stage to separate solids that have not gone into solution. The unreacted fractions of the solid fuel can then be supplied for further use, in particular combustion in a power plant. Subsequently, typically mineral constituents that have gone into solution are separated by precipitation or extraction. In order subsequently to obtain the carboxylic acid, there is an extraction, a membrane separation or a rectification, in particular a reactive rectification. For all separation steps, the process conditions should be such that the catalyst remains in the aqueous solution. The solution, which is then depleted of mineral constituents and carboxylic acid but containing the catalyst, is then returned to the reactor. In an advantageous alternative development of the invention, the formic acid by means of a

Generated periodic acid method. This method is particularly suitable for solid fuels containing sugars. Under the action of periodic acid, these sugars react to formic acid. This process advantageously takes place in an aqueous environment under mild reaction conditions. The reaction temperature is almost ambient.

In a further advantageous embodiment and further development of the invention, the formic acid is purified after the catalytic production. Furthermore, the formic acid can be stored after this process step. The formic acid can be stored from the solid fuel after the preparation or after a possible treatment advantageously in liquid or in solid form. Advantageously, only small volumes are needed for storage here. In particular, compared to the storage of synthesis gas, the required storage volume is reduced significantly. Furthermore, the storage of formic acid can take place at ambient pressure. This reduces the expenditure on equipment of the storage containers. The storage of the formic acid can alternatively take place in liquid form at high pressure or the formic acid is brought to high pressure before decomposition, so that the two decomposition reactions of the formic acid can also take place at high pressure and a gas mixture with a high pressure. The decomposition pressure can be adjusted in this way so that it is optimized for a downstream process. For use In a gas turbine, the pressure is typically between 1 bar to 200 bar, in particular between 1 bar to 30 bar.

In a further advantageous embodiment of the invention, the gas turbine is integrated with a steam turbine to a so-called gas and steam (CCGT) power plant and thus advantageously increases the efficiency. It is also conceivable to extract heat from the combined cycle power plant, so that the power plant can also be operated as a combined heat and power plant. This is particularly advantageous when the system has only a small capacity to increase the fuel efficiency and to improve the economy. In smaller systems, the operation of a downstream circuit with an organic working medium (Organic Rankine Cycle) is conceivable.

In a further advantageous embodiment and development, the waste heat of the first reactor is used to generate steam or to heat water. The heat can then be used advantageously in the steam cycle of the gas and steam power plant. By using the waste heat of the first reactor, the efficiency of the entire system increases advantageously. In a further advantageous embodiment of the invention, heat is taken from the power plant, in particular the steam cycle, or heat of a warm exhaust gas stream and fed to the second and / or third reactor. In a further advantageous embodiment and development of the invention, the regeneration of the

Polyoxometalate catalyst with air, in particular with the oxygen contained in the air, at elevated pressure from the compressor of the gas turbine. The pressure is typically less than 30 bar.

In a further advantageous embodiment and development of the invention, the exhaust gases from the generation of Formic acid either supplied to the gas turbine or burned. Advantageously, this further generates an increase in the efficiency of the system. In a further advantageous embodiment of the invention, the integrated power plant as a work machine comprises a gas turbine, an internal combustion engine or a fuel cell. In a further advantageous embodiment of the invention, the integrated power plant comprises a steam turbine for generating electricity by means of steam. Advantageously then increases the efficiency of the integrated power plant. Further embodiments and further features of the invention will be explained in more detail with reference to the following schematic figures.

Showing:

Figure 1 is a process flow diagram of an integrated power plant for operation with formic acid;

FIG. 2 shows a process flow diagram for producing the formic acid with a polyoxometalate catalyst and subsequent purification.

FIG. 1 shows an overview of an integrated power plant 1 for operation with formic acid 4. First, the dissolved solid fuel 25, in this example crude lignite with a water content greater than 30%, is led into a first reactor 3. The formic acid 4 is prepared by means of a polyoxometalate catalyst in an aqueous environment. The resulting second exhaust gas 27 is first led out of the process. The resulting formic acid 4 in an aqueous environment is then passed into a formic acid cleaning and separation device 5. After successful purification, the purified formic acid 6 is added to an aldehyde. Sensure memory 7 stored. Advantageously, this storage is done at ambient pressure and ambient temperature. On the one hand, this is particularly favorable and, on the other hand, less expensive in the use of apparatus. The purified formic acid 6 is then fed to a second 8 and a third reactor 9. In the second reactor 8, the purified formic acid 6 reacts to carbon monoxide 10 and water 11. The reaction temperature is more than 100 ° C. The reaction can be either non-catalytic or catalytic. A portion of the water 11 is then condensed in a condenser 12 and led out of the system. The carbon monoxide 10 leaves the condenser 12 at a concentration of more than 40%. In the third reactor 9, the purified formic acid 6 reacts to form a gas mixture comprising hydrogen 13 and carbon dioxide 36. This reaction typically takes place at temperatures below 100 ° C. on heterogeneous or homogeneous catalysts. It is possible to partially or completely separate the carbon dioxide 36. The gas mixture comprising hydrogen 13, carbon dioxide 36, water 11 and carbon monoxide 10 is then fed as synthesis gas to the gas turbine 14 for generating electricity.

The resulting in the gas turbine 14 hot exhaust gas 16 is used in a steam process. The waste heat of the hot exhaust gas 16 is used to first heat water 18 in a steam generator 17 and then to evaporate. The cold exhaust 44 leaves the system. The hot water vapor 19 is then fed into a steam turbine 20, thus generating electricity as well. The cooled and partially condensed water vapor 21 is passed through a condenser 22 and then returned to the steam train 17 again. Since the exhaust gas 27 also exits at an elevated temperature, it is likewise possible to guide it via a heat exchanger and thus utilize its heat energy.

As an alternative to a gas turbine, depending on the power range of the power plant, gas engines may be used to generate electricity. Fuel cells or other engines are used. Particularly in the kilowatt range down to the lower double-digit megawatt range, gas engines are preferred to gas turbines.

Particularly advantageous in this integrated power plant 1 is that the formic acid 4 can be stored as a liquid or solid at ambient pressure. Thus, a decoupling of the formic acid production process and the gas turbine process is possible. This enormously increases the flexibility of the integrated power plant 1. The integrated power plant 1 allows the generation of electricity from a solid fuel with gas turbines through the intermediate step of formic acid production. This increases the efficiency and flexibility compared to steam power plants. Purification of the products from the second and third reactor 8, 9 is basically not necessary, since the formic acid 4 is present purified as educt. Only when using a hydrogen fuel cell, a separation of the carbon dioxide 36 from the third reactor 9 may be necessary, for example, by C0 ₂ -Wäche or pressure swing adsorption.

Figure 2 shows in detail the preparation of formic acid 4 and the subsequent separation and purification process. First, solid fuel 2, raw lignite, additives 23, in this example surfactants, and water as solvent 24 are fed into a first storage vessel 37. The solid fuel 2 is brought into solution. The dissolved solid fuel 25 is then fed into the first reactor 3. This reactor 3 is equipped with a stirrer. About the agitator can be a gas mixture comprising oxygen and

Nitrogen, especially air 26, continuously add to the system. Advantageously, this allows a continuous oxidation of the catalyst in order to reactivate it after the reaction. The catalyst used is a polyoxometalate

Catalyst used. The temperature in the reactor is typically 40 ° C to 150 ° C, especially 60 ° C to 95 ° C. The pressure in the reactor is typically between 1 bar and 100 bar, in particular between 1 bar and 30 bar. The resulting during the formic acid production second exhaust 27 is led out of the process. The reaction is exothermic. The heat is dissipated, so that there is typically a temperature between 60 ° C and 90 ° C in the reactor.

Alternatively, it is also conceivable that the dissolution step and the reaction step are carried out together in a vessel. The solid fuel 2 and the additive 23 are added directly to the reactor.

Subsequently, the reaction mixture is passed through a solids filter 28 with formic acid 4. The solids that have not dissolved or that have formed during the reaction are separated. The proportion of undissolved solid fuel can then be used and, for example, a combustion in a combined heat and power station to be returned or returned to the reactor 37. The solids-free formic acid 41 in aqueous solution is then fed into a desalting device 38. By means of precipitation reagent 29 mineral components are precipitated and led out of the system. The salt-free formic acid 42 is then fed to a three-stage extraction process. Ideally, the formic acid 42 passes into the extraction phase, but the catalyst remains in the solvent so that it can be recycled to the reactor 3. The formic acid 35 contained in the extraction agent 34 is then removed from the system. Formic acid and extractant are then separated from one another by a thermal separation process, in particular a distillation or a reactive rectification. Alternatively, separation methods such as membrane processes can be used.

Claims

claims

1. Method for operating an integrated power plant (1) with formic acid (4) with the following steps:

catalytic production of formic acid (4) from a solid fuel (2) at low temperatures in a first reactor (3),

Decomposing formic acid into a first gas mixture comprising hydrogen (13) and carbon dioxide (36) in a second reactor (9) and / or

Decomposing formic acid into a second gas mixture comprising carbon monoxide (10) and water (11) in a third reactor (8),

- Leading the first and / or second gas mixture as fuel gas in a working machine for generating electricity.

2. The method of claim 1, wherein by means of the waste heat of the working machine and / or by means of the waste heat of the first reactor (3) steam (19) is generated or heated.

3. The method of claim 2, wherein the steam (19) is fed into a steam turbine (20) for generating electricity.

4. The method according to any one of the preceding claims, wherein the formic acid (4) by means of a catalytic reaction with a polyoxometalate catalyst of the form H _{3 + y} [PMo _x V _y 0 ₄ o] is produced as a catalyst, wherein l <y <13 , -1 <χ <11 and x + y = 12, where x and y are each an integer.

5. The method according to any one of claims 1 to 3, wherein the production of formic acid (4) by means of a

Periodic acid method takes place.

6. The method according to any one of the preceding claims, wherein the formic acid (4) is purified after the catalytic production.

7. The method according to any one of the preceding claims, wherein the formic acid (4) is stored after the catalytic generating.

8. The method according to any one of the preceding claims, wherein the second reactor (8) and / or the third reactor (9) by means of the steam (19), are heated by means of warm water or by means of a warm exhaust gas stream.

9. The method according to any one of claims 1 to 4 or 6 to 8, wherein for the catalytic reaction with the

Polyoxometalatkatalysator air is removed at a maximum pressure of 30 bar from a compressor of the gas turbine (14).

10. The method according to any one of the preceding claims, wherein exhaust gases (27) from the generation of the formic acid of the gas turbine (14) are supplied or burned.

11. The method according to any one of the preceding claims, wherein as solid fuel (2) peat, lignite, coal or biomass is used.

12. The method according to any one of the preceding claims, wherein the temperature during the production of formic acid (4) in a range of 1 ° C to 150 ° C.

13. Integrated power plant (1) for operation with formic acid (4) from a solid fuel (2) comprising:

- A first reactor (3) for the catalytic production of

Formic acid (4) from a solid fuel (2) at low temperatures,

- A second reactor (9) for decomposing formic acid (4) to a first gas mixture comprising hydrogen (13) and carbon dioxide (36) and / or a third reactor (8) for decomposing formic acid (4) into a second gas mixture comprising carbon monoxide (10) and water (11),

- A working machine for generating electricity by means of the first and / or second gas mixture.

14. An integrated power plant (1) according to claim 14, wherein the work machine is a gas turbine (14), an internal combustion engine or a fuel cell.

15. Integrated power plant (1) according to claim 13 or 14 with a steam turbine (20) for generating electricity by means of steam (19) which has been heated or generated by the waste heat (16) of the working machine.