Method for supplying process steam and process engineering plant for using process steam

Abstract

A method is described and illustrated using geothermal energy to provide process steam (22) for a process, particularly a process engineering process, in which the geothermal heat of a heated thermal fluid (3) at a geothermal source is used to provide geothermal steam (6) and upgrade steam (12, 16) is used to upgrade the geothermal steam (6), during which the geothermal steam (6) is simultaneously compressed and heated, to enable climate-friendly, simpler, more efficient and more economical operation.

Description

[Technical field]

[0001] The present invention relates to a method for providing process steam for a process, in particular a process engineering process, using geothermal heat. Furthermore, the present invention relates to a process engineering plant, in particular for paper manufacturing, for using process steam provided using geothermal heat. [Background technology]

[0002] Geothermal energy refers to the energy present in the form of heat below the Earth's surface. When geothermal sources are used that are up to 400 m deep below the surface, it is called shallow geothermal energy, and deeper still, deep geothermal energy. The possible applications of deep geothermal energy are divided into hydrothermal systems and bedrock thermal systems. In hydrothermal systems, naturally occurring warm groundwater is used. In bedrock thermal systems, the energy stored in the rock is mainly used, for example by deep geothermal probes or by injection of water into the rock. In most cases, the temperature level of usable geothermal energy is low, so it is only used for heating or cooling buildings. However, in some places, the temperature is high enough that process steam can be extracted from the geothermal energy for use in process engineering plants.

[0003] In this context, a method is known in which water is converted into process steam by indirect heat exchange with hot water in an evaporator. This process steam can then be used in a process engineering plant. However, this requires that hot water is available at a temperature level higher than that of the process steam. However, the temperature of the hot water is often not sufficient for this purpose, so various methods have been proposed to provide process steam at a temperature level higher than that of the hot water. For example, in order to provide process steam at the desired temperature level, it is known to expand hot water in a flash tank to produce steam and to burn fossil fuels to heat the hot water or steam. Alternatively, the steam produced in the flash tank can be heated to the required process steam temperature or brought to the required process steam pressure by mechanical compression. In a further variant of the method, the steam from the flash tank is first used to evaporate a process fluid. The temperature of the steam of the process fluid is then increased by mechanical compression to obtain process steam at the desired temperature or pressure level. With the increase in pressure, the temperature increases. This temperature can be appropriately adjusted or changed in further process steps. Furthermore, in this context, the use of closed heat pumps is also known. However, these methods are severely limited in terms of the temperature of the hot water and the temperatures that can be achieved due to the required heat pump medium. Known methods using closed heat pumps can achieve temperatures of up to 160° C. Therefore, there is a further need for simpler, more efficient and economical methods and process engineering plants. Summary of the Invention [Means for solving the problem]

[0004] The present invention is therefore based on the object of designing and further developing methods and process engineering plants in any case of the type mentioned at the beginning and described in more detail above, in such a way that a more climate-friendly, simpler, more efficient and economical operation is possible.

[0005] This object is achieved according to claim 1 by a method for using geothermal heat to supply process steam for a process, in particular a process engineering process, in which: - geothermal heat of a thermal fluid heated at a geothermal source is used to provide geothermal steam; - Upgrade steam is used to upgrade geothermal steam, - Geothermal steam is compressed and heated simultaneously during the upgrade.

[0006] The object is also achieved according to claim 10, in particular by a process engineering plant for using geothermal process steam, in particular for paper manufacturing, as defined in any one of claims 1 to 9. The process engineering plant comprises a geothermal station for heating a thermal fluid by means of geothermal heat from a geothermal source in the earth and for using the geothermal heat of this thermal fluid to supply geothermal steam, a source of upgrading steam and an upgrading device for simultaneously compressing and heating the geothermal steam by means of the upgrading steam.

[0007] Thus, according to the invention, the geothermal steam and the upgrading steam are used to generate process steam. The geothermal steam is generated using a geothermal heat source. For this purpose, a heated thermal fluid, preferably water, is extracted from the earth and used to generate geothermal steam. In this process, the thermal fluid can be expanded, for example in a flash tank, especially if it is in liquid form. The steam leaving the flash tank can then be used as geothermal steam or can be further heated. In particular if the thermal fluid is initially present as a liquid-vapor mixture, this thermal fluid can be separated into steam and liquid in the flash tank. If the thermal fluid is further partially expanded, part of the liquid phase in the flash tank can also be evaporated.

[0008] It is also conceivable that the thermal fluid first transfers part of its heat to another fluid to evaporate or at least heat this fluid. This is particularly useful, for example, to provide a thermal circuit when undesirable impurities of the thermal fluid are expected in the geothermal source. The heat of this thermal fluid can then be transferred first to water, or another medium that is easier to handle. The heated water or other medium can be separated into vapor and liquid in a flash tank and / or partially expanded to produce steam. This steam can be used as geothermal steam as is, or can be further heated in a separate step beforehand.

[0009] If the thermal fluid in the geothermal source is heated to a temperature below 100° C., the thermal fluid can be further heated using another heat source to generate geothermal steam from the correspondingly heated thermal fluid. If necessary, the heat of the thermal fluid can be first transferred to water or another medium, which can then be further heated in a further step to generate geothermal steam.

[0010] Geothermal steam can be used or supplied at pressures lower than ambient or standard pressure, especially when only low-temperature level thermal fluids are available. This entails energy advantages, since only a low enthalpy of vaporization is required, if necessary. The temperature of the geothermal steam can therefore be much lower than the 100°C required under normal conditions. In this case, by subsequent upgrading, process steam at pressures significantly higher than ambient or standard pressure can still be obtained without any problems. In other words, the pressure level of the geothermal steam is not necessarily limited downwards by the ambient or standard pressure. Rather, depending on the application, the pressure of the geothermal steam can be appropriately selected.

[0011] The upgrading steam can be obtained or available in any way other than using geothermal heat. This allows the upgrading steam to energetically upgrade the geothermal steam by upgrading. In this context upgrading is to be understood as a method step of simultaneously heating and compressing the geothermal steam. Heating and compression cannot be divided into two separate method steps that are decoupled from each other. In principle this can therefore also be referred to as thermal compression.

[0012] The above process can be used to provide process steam in a process engineering plant. For this purpose, a geothermal station is needed to heat a thermal fluid by a geothermal source in the earth. In addition, in the geothermal station, geothermal heat is used to generate geothermal steam from the thermal fluid. Furthermore, an upgrade steam source is needed, in which the upgrade steam, if needed, can already be available, i.e. it does not have to be generated separately. The upgrade steam is used in an upgrading device to upgrade the geothermal steam by simultaneously compressing and heating the geothermal steam with the upgrade steam.

[0013] Particularly suitable here is the case when the process engineering plant is a paper plant, where the advantages of the method are particularly effective, since in paper production there is a very large demand for process steam at least at medium to high temperature and medium to high pressure levels, which can be ensured in a particularly climate-friendly, simple, efficient and economical manner in the above-mentioned manner.

[0014] In a first particularly preferred embodiment of the method, upgrading steam is used to upgrade the geothermal steam, which has a pressure and temperature higher than the pressure and temperature of the geothermal steam. This is particularly easy to implement. For example, the equipment and process engineering allows for a mixing of the upgrading steam with the geothermal steam during the upgrading. However, this is not essential. It is also possible to compress and heat the geothermal steam simultaneously during the upgrading without mixing the upgrading steam with the geothermal steam. A particularly simple example of this is indirect heat transfer. In addition, it is also conceivable to upgrade the geothermal steam with upgrading steam, which has a lower pressure and temperature than the geothermal steam. However, in principle, this would lead to higher equipment costs.

[0015] For simplicity, it is convenient to heat and compress the geothermal steam with the upgrading steam by direct heat exchange in the steam jet compressor. In this process, the upgrading steam is partially expanded through the throttle of the steam jet compressor, so that the upgrading steam reaches a high speed and thus draws geothermal steam from the secondary line at a pressure lower than the initial pressure of the upgrading steam. This geothermal steam is then mixed with the upgrading steam in the process and accelerated. The steam generated by mixing the geothermal steam and the upgrading steam is then decelerated in a diffuser. Thus, process steam with sufficient pressure and sufficient temperature is generated. The pressure and temperature of the process steam are preferably between those of the upgrading steam and the geothermal steam.

[0016] Alternatively or additionally, a compressor with a turbine driven by the upgrading steam can be used for heating and compressing the geothermal steam with the upgrading steam. This basically allows more flexibility in terms of the amount and type of geothermal steam upgrading. Here, if necessary, mixing of the upgrading steam with the geothermal steam can be omitted. The upgrading steam drives a turbine separately from the geothermal steam. In this case, the turbine drives a compressor. In the compressor, the geothermal steam is upgraded in at least one stage. This upgrading takes place while simultaneously compressing and heating the geothermal steam.

[0017] Particularly suitable is the case when a turbo-compressor of a turbocharger driven by a turbine is used as the compressor. In such a turbocharger, the turbine and the turbo-compressor can be arranged on a common shaft, so that the turbine and the turbo-compressor are directly coupled, if necessary without an acceleration ratio, although this is not essential. Any kind of gearbox can also be provided between the turbine and the turbo-compressor in order to provide an acceleration ratio, or possibly a reduction ratio, between the turbine and the turbo-compressor. In this case, the turbine can be operated with the available upgrade steam. The process parameters of the upgrade steam are of less importance for the upgrading of geothermal steam. Here, in principle, what is more important is the available mass flow rate of the upgrade steam. The upgrade steam in this case can therefore also easily have a temperature and pressure lower than that of the geothermal steam. The design of the turbocharger allows a suitable upgrading of geothermal steam in terms of pressure and temperature in the turbo-compressor of the turbocharger. The turbo-compressor is driven by the upgrade steam and the turbine. The turbine and the turbo-compressor are coupled via a shaft and, if necessary, also via a gearbox. The geothermal steam is compressed in a turbocompressor and further heated by the heat generated in this process.

[0018] The upgrading steam does not necessarily have to be fully expanded when passing through the turbine. If the upgrading steam is only partially expanded in the turbine, it may be useful to increase efficiency if this partially expanded upgrading steam is mixed with the geothermal steam after it leaves the turbine, especially if it is used to drive a steam jet compressor. This is of particular interest when a steam jet compressor is used for further heating and compression of the geothermal steam after it leaves the compressor. In this case, it is preferred that this compressor may be the turbo compressor of a turbocharger, although this is not essential.

[0019] It may also be envisaged to expand the upgrade steam in a turbine, such as a turbocharger, until the pressure level of the upgrade steam after leaving the turbine corresponds at least approximately to the pressure level of the geothermal steam compressed in the turbocompressor. The resulting upgrade steam can then be used efficiently by mixing the partially expanded upgrade steam with the compressed geothermal steam. In this case, a steam jet compressor is not necessary. A simple mixing chamber is sufficient for this purpose. In addition, the temperature levels of the compressed geothermal steam and the partially expanded upgrade steam can also correspond at least approximately to each other. However, this is not essential. It is usually advantageous if the temperature of the upgrade steam before mixing is significantly higher than the compressed geothermal steam. In this case, not only the pressure of the upgrade steam but also its temperature will be used particularly advantageously. However, mixing of the partially expanded upgrade steam with compressed geothermal steam is also possible if the temperature of the upgrade steam before mixing is lower than the compressed geothermal steam. In both cases, process steam can be produced by mixing the compressed geothermal steam leaving the turbocompressor with the upgrade steam leaving the turbine. This allows the partially expanded upgrading steam to be used for running subsequent processes, particularly process engineering processes.

[0020] The thermal fluid may be contaminated with respective impurities, for example due to underground heating at the geothermal source. In this case, it may be appropriate if the thermal fluid first transfers the geothermal heat by indirect heat exchange to water or another medium, which then takes over the further transport of the geothermal heat in the direction of the process engineering process. In such a case, it may be even more appropriate if the thermal fluid is not water, but some other heat transfer medium. In this case, it is not necessary to evaporate the thermal fluid, for example to produce water vapor, so that this does not have to be taken into account when selecting the thermal fluid. Nevertheless, it may also be appropriate to use water as the thermal fluid for the sake of simplicity.

[0021] Regardless of the choice of thermal fluid, it is particularly simple and reliable to at least partially evaporate the water to produce geothermal steam by indirect heat exchange with the thermal fluid. If the water is only partially evaporated to produce geothermal steam, it is advantageous to direct the geothermal steam and the unevaporated water to a flash tank for separation of the geothermal steam and the water. If the pressure in the flash tank is further significantly reduced, at least a part of the water can be evaporated to geothermal steam. In this case, the correspondingly recovered water steam can be used as geothermal steam for upgrading by simultaneous increase in pressure and temperature with the upgrading steam.

[0022] For economic reasons, fossil fuels can be burned, for example in a boiler, to obtain the upgrading steam. However, in order to increase the overall efficiency, and also from an ecological point of view, it may be advantageous if biomass, biogas and / or waste is used to generate the upgrading steam as at least a partial replacement for fossil fuels. In this case, if necessary, the waste can also be biomass. This is particularly applicable if biomass, biogas and / or waste is generated and / or generated in the process engineering plant to be heated, in particular in the process to which the process steam is supplied, in particular in the process engineering process. However, it is also possible to completely dispense with the combustion of fossil fuels, biomass, biogas or waste to generate the upgrading steam. Biogas here can also be understood as synthetically, in particular regeneratively, produced hydrogen and methane. Corresponding alternative methods are known to the person skilled in the art and are fully described in the prior art.

[0023] The method can be used particularly efficiently if a heated thermal fluid is used to supply the geothermal steam, the heated fluid having a temperature of at least 60° C., at least 80° C., in particular at least 100° C. In this case, only a moderate upgrading of the geothermal steam is required. Furthermore, alternatively or additionally, the efficiency increase can be helped if a heated thermal fluid is used to supply the geothermal steam, the heated fluid having a temperature of at most 220° C., preferably at most 180° C., in particular at most 140° C. Otherwise, in most cases, only a small upgrade is required, which can only partially justify the process engineering and equipment costs.

[0024] For the same reasons, it may alternatively or additionally be preferred if the geothermal steam is not too cold and / or not too hot before the upgrading using the upgrading steam, whereby high efficiencies are achieved if the temperature of the geothermal steam before upgrading is at least 60° C., at least 80° C., in particular at least 100° C. However, it may also be envisaged that the temperature of the geothermal steam before upgrading is at most 220° C., preferably at most 180° C., in particular at most 140° C.

[0025] The heat of the thermal fluid can be easily and efficiently used if the geothermal steam is heated during upgrading by at least 20° C., preferably by at least 50° C., in particular by at least 100° C. However, this is also true if, alternatively or additionally, the geothermal steam is compressed by at least 1 bar, preferably by at least 2 bar, in particular by at least 3 bar, during upgrading.

[0026] In a first particularly preferred embodiment of the process engineering plant, the source of upgrade steam is a source designed to provide upgrade steam at a pressure and temperature higher than that of the geothermal steam, in such a case upgrading of the geothermal steam can be easily carried out in terms of equipment and process engineering, for example by mixing the upgrade steam with the geothermal steam.

[0027] In particular, in such cases, the upgrading device preferably comprises a steam jet compressor to provide process steam having a higher pressure and temperature than the initial pressure of the geothermal steam, and the geothermal steam and the upgrading steam are suitably combined in the steam jet compressor, which is easy to achieve and can be done efficiently, although this is not essential in this or any other case.

[0028] Alternatively or additionally, the upgrading device comprises a compressor with a turbine driven by the upgrading steam to heat and compress the geothermal steam. This can be done particularly easily and at the same time economically if the compressor is a turbocharger thermocompressor. In this case, the upgrading steam can drive the turbocharger turbine, which in turn drives the turbocharger thermocompressor to compress the geothermal steam. When the geothermal steam is compressed in the thermocompressor, a lot of heat is generated, so that the geothermal steam is heated at the same time as it is compressed.

[0029] For further energy optimization, a connection line can be provided for feeding the partially expanded upgrading steam from the turbine to a steam jet compressor, which then serves to further heat and compress the geothermal steam already partially heated and compressed in the turbo compressor. Although the use of a steam jet compressor for mixing the partially expanded upgrading steam with the partially compressed geothermal steam is preferred here, this mixing can also take place in a mixing chamber other than the steam jet compressor.

[0030] To avoid unnecessary contamination by the thermal fluid, and also to keep maintenance costs low, it may be advisable to pass the thermal fluid through a thermal circuit, which has an indirect heat exchanger for transferring the heat of the thermal fluid to water or another medium.

[0031] If this thermal fluid is hotter than 100° C. and at least partially liquid, it can be pumped into a flash tank to generate steam. If the thermal fluid is water, water can be added to the part of the thermal fluid that has not been evaporated in the process before it is used again for geothermal heating of the earth. However, it is also possible to evaporate the water in an evaporator by first transferring geothermal heat from the thermal fluid of the thermal circuit to water in the evaporator, which is indirectly heated. In principle, it does not matter whether water has already been used as a thermal fluid. Moreover, from an energy and design point of view, it is usually expedient if the above-mentioned heat exchanger of the thermal circuit forms part of the evaporator for at least partial evaporation of water and supply of geothermal steam.

[0032] In any case, if upgrading steam is not available, evaporators fuelled by fossil fuels, biogas and / or biomass can be used to generate upgrading steam and / or geothermal steam simply and economically, although in principle any other process and plant for generating steam or for supplying upgrading steam and / or geothermal steam is also conceivable.

[0033] In the following the invention will be explained in more detail by means of drawings which merely show some example embodiments. [Brief description of the drawings]

[0034] [Figure 1] FIG. 1 is a schematic diagram of a process engineering plant according to the invention for using geothermal heat. [Diagram 2] FIG. 1 is a schematic diagram of a first method according to the invention for using geothermal heat. [Diagram 3] FIG. 2 is a schematic diagram of a second method according to the invention for using geothermal heat. [Figure 4] FIG. 2 is a schematic diagram of a third method according to the invention for using geothermal heat. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] In FIG. 1, a process engineering plant 1 for paper production is shown. In this process engineering plant 1, process steam is used, which is generated using geothermal heat. To use the geothermal heat, a geothermal station 2 is provided. In the geothermal station 2, a thermal fluid 3 is pumped into the ground in order to be heated by a geothermal source in the ground. The thermal fluid 3 can be water for simplicity. The thermal fluid 3 thus heated is returned to the surface 4, where it is fed to an evaporator 5. In the evaporator 5, geothermal steam 6 is generated from the thermal fluid 3. This geothermal steam is then fed to a papermaking section 7. During paper production in the papermaking section 7, wastewater is generated. This wastewater is treated in a wastewater treatment unit 8, which simultaneously generates biogas 9. To generate the biogas 9, biomass generated elsewhere in the overall process can also be used, if necessary. The biogas 9 is fed to a combined heat and power plant 10, where it is burned together with natural gas 11 to generate steam 12 for upgrading. Furthermore, a biomass power plant 13 is provided. The biomass power plant 13 generates, on the one hand, electricity 15 from biomass 14 and, on the other hand, also upgrade steam 16. If necessary, the biomass power plant 13 or the cogeneration plant 10 can be omitted. However, an entirely different source of upgrade steam 12, 16 can also be used. However, regardless of how it is generated, the upgrade steam 12, 16 has a higher pressure than the geothermal steam 6. In addition, the temperature of the upgrade steam 12, 16 is higher than the temperature of the geothermal steam 6.

[0036] In the papermaking section 7, process steam is generated from the upgrading steam 12, 16 and the geothermal steam 6. This process steam is used for papermaking, in particular for heating certain processes during papermaking. For this purpose, various methods are possible, of which three different methods are shown as examples in Figures 2 to 4. These methods are described below.

[0037] FIG. 2 shows a method for heating a thermal fluid 3 to a temperature higher than 100° C. in a geothermal source not shown in the ground. After the heated thermal fluid 3 is returned to the surface 4, its heat is used in an evaporator 5 to evaporate water 17. This water 17 is fed as geothermal steam 6 to a steam jet compressor 18. The steam jet compressor 18 is operated by the upgrading steam 12, 16. The upgrading steam 12, 16 is accelerated in the steam jet compressor 18 by partial expansion via a throttle 19, so that after the throttle 19 the geothermal steam 6 is sucked into a mixing chamber 20 where it is mixed with the upgrading steam 12, 16. This steam is then led to a diffuser 21 and thus slowed down again, so that process steam 22 is generated at a pressure and temperature higher than that of the geothermal steam 6. Thus, the geothermal steam 6 has been upgraded in pressure and temperature through the use of the upgrading steam 12, 16 so that it can then be efficiently used as process steam 22 for papermaking in the papermaking section 7.

[0038] Instead of the method shown in Figure 2, the thermal fluid can also be expanded in a flash tank, for example. The resulting steam can be fed to the steam jet compressor as geothermal steam. In this case, the prior transfer of geothermal heat from the thermal fluid to water can be omitted.

[0039] Fig. 3 shows a method for heating a thermal fluid 3 to a temperature below 100°C in a geothermal source not shown in the ground. After the heated thermal fluid 3 is returned to the surface 4, an indirect heat exchange with water 17 takes place in a heat exchanger 23, whereby geothermal heat is transferred to the water 17. The water 17 is then evaporated in an evaporator 5 of a boiler 25 fuelled by fossil and / or renewable fuels 24. However, evaporators 5 operated in different ways are also conceivable. In the illustrated embodiment preferred in this respect, the geothermal steam 6 leaves the evaporator 5 and is fed to a steam jet compressor 18 where it is upgraded by a simultaneous increase in temperature and pressure by the upgrading steam 12, 16 driving the steam jet compressor 18 as described above.

[0040] Alternatively to the method shown in FIG. 3, the thermal fluid 3 can also be expanded in a flash tank, for example. The steam resulting from this process can also be fed to the steam jet compressor 18 as geothermal steam 6. In this case, the prior transfer of geothermal heat from the thermal fluid 3 to the water 17 can be omitted. However, it is also conceivable to evaporate the thermal fluid 3 in the evaporator 5 by adding additional heat. The steam obtained can then be fed directly to the steam jet compressor 18 as geothermal steam 6 or used to evaporate the water 17. In the latter case, the water vapor thus generated is fed to the steam jet compressor 18 as geothermal steam 6.

[0041] FIG. 4 shows a method for heating a thermal fluid 3 to a temperature above 100° C. in a geothermal source in the ground (not shown). After the heated thermal fluid 3 is returned to the surface 4, the heat of the thermal fluid 3 is used in an evaporator 5 to evaporate water 17, which is then supplied as geothermal steam 6 to a turbocharger 26. This thermal fluid does not necessarily have to be circulated. The thermal fluid could also be pumped from the ground at one location and reinjected into the ground at another location. The same thermal fluid is not necessarily used, particularly if the thermal fluid flows in the ground as naturally occurring groundwater, but rather different thermal fluids from the same source can always be used as needed.

[0042] The turbocharger 26 has a turbine 27. The turbine 27 is connected to a turbocompressor 29 via a shaft 28. The upgrading steam 12, 16 is fed to the turbine 27 and partially expanded therein, driving the shaft 28. The shaft 28 then drives the turbocompressor 29. The turbocompressor 29 simultaneously compresses and heats the geothermal steam 6. In the illustrated embodiment which is preferred in this respect, the compressed geothermal steam 6 is then mixed in a mixing chamber 30 with the partially expanded upgrading steam 12, 16 for further upgrading by simultaneous increase in pressure and temperature in addition to upgrading the geothermal steam 6 by simultaneous increase in pressure and temperature in the turbocharger 26. For this purpose, the turbine 27 is connected to the mixing chamber 30 via a connecting line 31. The mixing chamber 30 can preferably be the mixing chamber of a steam jet compressor. Generating process steam 22 by subsequent mixing of compressed geothermal steam 6 with partially expanded upgrading steam 12, 16 can be particularly expedient if the upgrading steam 12, 16 is at a much higher pressure than the compressed geothermal steam 6. This is because it is preferred that the upgrading steam 12, 16 has a still higher pressure after partial expansion in the turbine 27 of the turbocharger 26 than the pressure of the compressed geothermal steam 6 after leaving the turbocompressor 29, although this is not essential.

[0043] Alternatively, it may be envisaged to expand the upgrading steam 12, 16 in the turbine 27 of the turbocharger 26 until the pressure level of the partially expanded upgrading steam 12, 16 after leaving the turbine 27 corresponds at least approximately to the pressure level of the compressed geothermal steam 6 after leaving the turbocompressor 29. In this case, mixing of the partially expanded upgrading steam 12, 16 with the geothermal steam 6 can take place without a steam jet compressor, if necessary in a very simple mixing chamber 30. The partially expanded upgrading steam 12, 16 together with the upgraded geothermal steam 6 can then be used as process steam 22 in further processes, in particular in process engineering processes.

[0044] As an alternative to the method shown in Fig. 4, the thermal fluid 3 can also be expanded, for example in a flash tank. The steam resulting from this process can also be supplied as geothermal steam 6 to the turbo compressor 29 of the turbocharger 26. In this case, the prior transfer of geothermal heat from the thermal fluid 3 to the water 17 can be omitted. [Explanation of symbols]

[0045] 1. Process Engineering Plant 2. Geothermal Station 3. Thermal Fluids 4 Earth's surface 5. Evaporator 6. Geothermal Steam 7 Papermaking Department 8 Water Treatment Unit 9. Biogas 10 Combined Heat and Power Plants 11. Natural Gas 12 Steam for Upgrades 13 Biomass Power Plant 14 Biomass 15. Electricity 16 Steam for Upgrades 17 water 18 Mixing chamber 19 Throttle 20 Mixing chamber 21 Diffuser 22 Process steam 23 Heat exchanger 24 Fuel 25 Boiler 26 Turbocharger 27 Turbine 28 Shaft 29 Turbo Compressor 30 Mixing chamber 31 Connection Line

Claims

1. 1. A method for using geothermal energy to supply process steam (22) for a process, in particular a process engineering process, in which the geothermal energy of a thermal fluid (3) heated in a geothermal source is used to supply geothermal steam (6), and upgrading steam (12, 16) is used to upgrade said geothermal steam (6), during which said geothermal steam (6) is simultaneously compressed and heated in a compressor.

2. 2. The method of claim 1, wherein the upgrading steam (12, 16) having a higher pressure and temperature than the pressure and temperature of the geothermal steam (6) is used to upgrade the geothermal steam (6) and / or the upgrading steam and the geothermal steam are mixed during upgrading.

3. 3. The method according to claim 1 or 2, wherein the geothermal steam (6) is heated and compressed by the upgrading steam (12, 16) by direct heat exchange in a steam jet compressor (18) and / or by a compressor with a turbine (27) driven by the upgrading steam (12, 16), preferably a turbo compressor (29) of a turbocharger (26) driven by the turbine (27) is used as compressor.

4. 4. The method of claim 3, wherein the partially expanded upgrading steam (12, 16) after exiting the turbine (17) is used to drive a steam jet compressor (18) to further heat and compress the geothermal steam (6) after exiting the compressor.

5. 4. The method of claim 3, wherein the partially expanded upgrading steam (12, 16) after leaving the turbine (17) and the upgraded geothermal steam (6) after leaving the turbo compressor (29) are mixed in a mixing chamber (30), and preferably the partially expanded upgrading steam (12, 16) and the upgraded geothermal steam (6) have at least approximately the same pressure before mixing in the mixing chamber (30).

6. 2. The method of claim 1, wherein the thermal fluid (3) transfers geothermal heat to water by indirect heat exchange, and preferably the water (17) is at least partially evaporated by the indirect heat exchange with the thermal fluid (3) to produce geothermal steam (6).

7. 7. The method according to claim 6, wherein the thermal fluid (3) or the water (17) heated and / or partially evaporated by the geothermal heat is evaporated, in particular completely, in an evaporator (5) to produce geothermal steam (6).

8. 2. The method of claim 1, wherein the upgrading steam (12, 16) is produced by combustion of fossil fuels (24), biogas, biomass (9, 14), and / or waste.

9. 2. The method according to claim 1, wherein the heated thermal fluid (3) having a temperature of at least 60°C, at least 80°C, in particular at least 100°C and / or at most 220°C, preferably at most 180°C, in particular at most 140°C, is used to supply geothermal steam (6) and / or the geothermal steam (6) has a temperature of at least 60°C, at least 80°C, in particular at least 100°C and / or at most 220°C, preferably at most 180°C, in particular at most 140°C, before upgrading.

10. 2. The method according to claim 1, wherein the geothermal steam (6) is heated to at least 20° C., preferably at least 50° C., in particular at least 100° C. during the upgrading and / or the geothermal steam (6) is compressed to at least 1 bar, preferably at least 2 bar, in particular at least 3 bar during the upgrading.

11. 1. A process engineering plant (1), in particular for paper manufacturing, for using process steam (22) supplied using geothermal heat as claimed in claim 1, comprising a geothermal station (2) for heating a thermal fluid (3) with geothermal heat from a geothermal source in the earth and for supplying geothermal steam (6) using the geothermal heat of the thermal fluid (3), a source of upgrading steam (12, 16) and an upgrading device for simultaneously compressing and heating the geothermal steam (6) with the upgrading steam (12, 16).

12. 12. A process engineering plant according to claim 11, characterized in that the source of upgrading steam (12, 16) is a source for supplying upgrading steam having a pressure and temperature higher than the pressure and temperature of the geothermal steam (6) and / or the upgrading device comprises a steam jet compressor (18) and / or a compressor with a turbine (27) driven by the upgrading steam (12, 16) for heating and compressing the geothermal steam (6), and preferably the compressor is a turbo compressor (29) of a turbocharger (26) driven by the turbine (27).

13. 13. A process engineering plant according to claim 12, characterized in that it is provided with a connection line (31) for supplying the partially expanded upgrading steam (12, 16) leaving the turbine (27) to a steam jet compressor (18) for further heating and compression of the geothermal steam (6) heated and compressed in the turbo compressor (29).

14. 13. A process engineering plant according to claim 12, characterized in that a thermal circuit is provided with an indirect heat exchanger with the thermal fluid (3) for transferring geothermal heat to water (17) and / or an evaporator (5) is provided for supplying geothermal steam (6), in particular from the water (17) heated by geothermal heat.

15. 15. A process engineering plant according to claim 14, characterized in that the heat exchanger (23) is part of the evaporator (5) for at least partially evaporating the water (17) to provide the geothermal steam (6).

16. 12. A process engineering plant according to claim 11, characterised in that it is provided with an evaporator (5) fuelled by a fossil fuel (24) and / or by biomass (9, 14) for supplying the geothermal steam (6) and / or the upgrading steam (12, 16).

Images