METHOD AND STEAM GENERATION DEVICE FOR THE GENERATION OF PROCESS STEAM

Description

[0001] The invention relates to a method for generating process steam using condensate recycled in the form of feedwater. The invention further relates to a steam generation device for generating process steam using condensate recycled in the form of feedwater according to such a method.

[0002] Steam generation plants are regularly used to produce process steam, which can drive a steam turbine or be used to heat an industrial process. Such industrial processes can be chemical processes or other manufacturing processes where heat is required at certain points or for carrying out specific process steps. These can be, for example, simple drying processes or similar operations.

[0003] Document JP 2013-2708 A relates to a steam generating device for producing process steam using condensate recycled in the form of feedwater, comprising a flash tank for separating the feedwater into a vapor phase and a liquid phase, a delivery device to a consumer device for the formation of condensate by condensing the process steam, and a return device for supplying condensate.

[0004] Steam generation systems typically comprise one or more steam generators in the form of steam boilers, which are fired with fossil or renewable fuels. The combustion energy released and the resulting hot flue gas are used to evaporate feedwater supplied to the steam boiler. Industrial steam boilers usually receive their feedwater under pressure via pipes, ensuring a continuous and efficient supply of process steam at a substantially constant pressure and temperature to a connected consumer device. As previously discussed, the type of consumer device can vary considerably. Regardless of its specific design, however, the process steam is condensed within the consumer device, releasing heat in the process.The condensate is usually recirculated via a return device and fed into the feedwater treatment system of the steam generation equipment, where it is degassed. The feedwater produced in this way is then re-evaporated in the steam boiler and supplied to the consumer equipment as process steam.

[0005] To utilize the energy of the flue gases in the steam generator as efficiently as possible and transfer it to the feedwater, it is desirable to supply the feedwater to the steam generator at the lowest possible temperature. However, other factors may preclude lowering certain temperatures. For example, to prevent corrosion, the feedwater should have a sufficiently high temperature to avoid falling below the acid dew point of the flue gas. Otherwise, the flue gas leaves the steam generator at a relatively high temperature, and thus with a considerable amount of unused heat. However, in the case of thermal degassing during feedwater treatment, the feedwater is produced at a temperature level of slightly above 100 °C.To lower the feedwater temperature after degassing, heat exchangers are used in which the feedwater is cooled, for example, by fresh water, which can then be added to the feedwater treatment system to compensate for condensate losses. These condensate losses can occur, for example, when a portion of the condensate is drained to remove non-volatile contaminants that accumulate in the water circuit.

[0006] A steam generator is generally understood to be one that may include, in particular, an economizer for preheating or heating the feedwater, an evaporator for vaporizing the preheated and / or heated feedwater, and a superheater for heating the steam to a desired temperature or at least to a temperature above the saturated steam temperature. In some cases, however, the economizer and / or the superheater may be omitted. The steam generator may also include a combustion system for generating the required heat by burning a fuel. However, this is not mandatory. The feedwater is preferably passed in counterflow with the heat transfer medium for preheating, heating, vaporization, and / or superheating, whereby the heat transfer medium may be, but does not have to be, flue gas.

[0007] Therefore, the present invention is based on the objective of designing and further developing the method and the steam generation device of the type mentioned at the outset and explained in more detail above in such a way that a higher efficiency can be achieved.

[0008] This problem is solved according to claim 1 by a method for generating process steam using condensate recycled in the form of feedwater, in which the process steam is supplied to a consumer device for the formation of a condensate by condensing the process steam, in which the condensate from the consumer device is fed to a feedwater treatment system for treatment, in which feedwater from the feedwater treatment system is separated into a vapor phase and a liquid phase in a flash tank, in which the liquid phase of the feedwater is evaporated in an evaporator to form raw steam, in which the vapor phase of the feedwater and the raw steam are compressed in at least one compressor to form process steam.

[0009] The aforementioned problem is further solved according to claim 9 by a steam generation device for generating process steam using condensate recycled in the form of feedwater, with a method according to any one of claims 1 to 8, with a flash tank for separating the feedwater into a vapor phase and a liquid phase, with an evaporator for evaporating the liquid phase of the feedwater to form raw steam, with at least one compressor for compressing the vapor phase of the feedwater and the raw steam to form process steam, with a delivery device to a consumer device for forming condensate by condensing the process steam, with a return device for supplying condensate and with a feedwater treatment system for treating the condensate to form feedwater.

[0010] The process begins with the generation of process steam in the steam generator and its transfer to a consumer unit, where the heat from the process steam is utilized, causing it to condense. The condensate produced during this condensation can be returned to the steam generator, where it is then fed into a feedwater treatment system. In the feedwater treatment system, the condensate is treated to prevent the accumulation of undesirable contaminants. These contaminants are primarily, but not necessarily, dissolved gases that can cause problems during the subsequent re-evaporation of the feedwater. Alternatively or additionally, liquids or solids can also be removed during feedwater treatment, optionally along with a portion of the condensate.The loss of condensate that occurs in this way, for example, can be compensated for by adding fresh water to the feedwater treatment.

[0011] The condensate treated in the feedwater treatment system is called feedwater and is transferred from the treatment system to a flash tank, where the feedwater pressure is reduced. As a result, a portion of the treated feedwater evaporates, forming a vapor phase in the flash tank. The remaining portion of the feedwater forms the liquid phase in the flash tank. This partial evaporation removes heat from the feedwater, so that both the vapor and liquid phases of the feedwater have a temperature significantly lower than that of the feedwater in the treatment system. The temperature of the feedwater in the flash tank can be reduced to such an extent that the liquid phase can be evaporated in an evaporator using a low-temperature heat source.For simplicity, the evaporator can be designed as a heat exchanger, in particular a shell-and-tube heat exchanger or a plate heat exchanger, with the heat source being a liquid and / or a gas. This can be a process stream whose heat cannot be used effectively elsewhere due to its low temperature. However, the heat from the process stream can be used to evaporate the liquid phase of the feedwater, which can then be cooled to a specific temperature, particularly below the temperature of the heat source, in the flash tank.

[0012] By evaporating the liquid phase of the feedwater, it can absorb heat that would otherwise be unusable or less effectively utilized. However, the resulting raw steam itself has a temperature level that also hinders its efficient use. For this reason, the raw steam is compressed in at least one compressor, which inevitably leads to its heating. Upon exiting the compressor, this heated raw steam is available as usable process steam.

[0013] Similarly, the vapor phase of the feedwater from the flash tank is fed to at least one compressor to raise its pressure and temperature, thereby generating usable process steam. The vapor phase of the feedwater from the flash tank and the raw steam from the evaporator can first be combined and then compressed together in at least one compressor. Alternatively, the vapor phase of the feedwater from the flash tank and the raw steam from the evaporator can be compressed separately in different compressors. The preferred method may depend, among other things, on the quantities of steam generated in the flash tank and the evaporator.

[0014] In particular, for carrying out the process described above, the steam generation unit includes a flash tank for separating the feedwater into a vapor phase and a liquid phase. The vapor phase in the flash tank is formed by the expansion of the treated feedwater. The remaining liquid phase of the feedwater, cooled in the flash tank, is evaporated in an evaporator by heat exchange with a heat source at a temperature level above that of the liquid phase from the flash tank, thus forming raw steam. At least one compressor is also provided, in which the vapor phase from the flash tank and the raw steam from the evaporator are compressed and heated. The vapor phase and the raw steam can be compressed at least partially together and / or at least partially separately from each other in one compressor or in several compressors.The at least one compressor thus serves to generate at least one process steam. The steam generation unit further comprises a delivery device for supplying the at least one process steam to a consumer unit and a return device for feeding condensate from the consumer unit back into the evaporation unit. Finally, a feedwater treatment system is also provided, which serves to treat the returned condensate before its re-evaporation in the evaporation unit and thus the generation of feedwater.

[0015] In principle, all known types of compressors are suitable for this application. These include, in particular, turbo compressors, piston compressors, and screw compressors.

[0016] The process and the steam generating device are described together below, without necessarily distinguishing between the process and the steam generating device in detail. However, it will be clear to a person skilled in the art from the respective context which features of the process and the steam generating device are particularly preferred.

[0017] In a first particularly preferred embodiment of the process, the condensate is at least partially degassed during feedwater treatment. Gases contained in the feedwater can damage the steam generator. In particular, oxygen (O₂) and / or carbon dioxide (CO₂) can pose a problem or be present in significant quantities in the condensate of the process steam. Therefore, in many cases, oxygen (O₂) and / or carbon dioxide (CO₂) are preferably driven off from the condensate during feedwater treatment.

[0018] For degassing the condensate in feedwater treatment, it can be advantageous, regardless of the gases to be driven off, to feed the condensate into the feedwater treatment system along with heating steam. The heating steam heats the condensate, particularly directly. Due to the high temperature, the gases are driven out of the feedwater and preferably extracted from the feedwater treatment system together with the vapors from the heating steam and / or evaporated condensate.

[0019] To make the treatment of the condensate for feedwater production, as well as the heating of the industrial process with process steam, energy-efficient, it is advantageous to supply the feedwater treatment system with condensate at a temperature between 60° and 100°C, preferably between 70°C and 80°C, and particularly at least substantially 80°C. The higher the temperature of the condensate, the less heating steam is required for its treatment. The lower the temperature of the condensate, the greater the amount of heat that can be transferred to the industrial process being heated. Furthermore, heat losses along the pipe lengths must be taken into account.

[0020] Alternatively or additionally, for the same reasons, the condensate can be treated in the feedwater treatment system at a pressure between 1 bar and 2 bar, preferably between 1.1 and 1.5 bar, and particularly at a pressure of at least substantially 1.2 bar. The lower the pressure, the more heat can be transferred to the industrial process. However, a certain pressure is required to sufficiently degas the condensate and to ensure adequate expansion of the feedwater in the flash tank. Therefore, the temperature of the feedwater in the feedwater treatment system is preferably above 100 °C, whereby little heating steam is required at a temperature between 102 °C and 108 °C, and particularly at a pressure of at least substantially 105 °C. At the same time, sufficient expansion and temperature reduction can be ensured in the flash tank.

[0021] To cool the liquid phase of the feedwater sufficiently and economically, it is generally advantageous to operate the flash tank at an absolute pressure between 0.07 bar and 0.9 bar. The lower the pressure, the colder the heat sources that can be used in the evaporator to vaporize the liquid phase of the feedwater. Operating the flash tank at a pressure between 0.12 bar and 0.8 bar can be particularly advantageous, although in many cases a pressure of at least 0.2 bar or 0.6 bar will represent a good compromise. For the reasons mentioned above in connection with pressure, and considering that pressure and temperature in the flash tank are interdependent, operating the flash tank at a temperature between 40 °C and 96 °C, preferably between 50 °C and 93.5 °C, is an alternative or additional option.Evaporation of the liquid phase of the feedwater at a low temperature level will be economically feasible in many cases at a temperature of at least substantially 60 °C or 85.9 °C.

[0022] To reduce the pressure in the flash tank to a level below that of the feedwater treatment system and, in particular, below ambient pressure, it is simpler if the compressor in the flash tank creates a corresponding vacuum. The pressure in the flash tank must be set so low that it is at least below the pressure in the feedwater treatment system. Otherwise, partial evaporation of the feedwater while simultaneously cooling it in the flash tank cannot be guaranteed.

[0023] Regardless, for many applications it is advantageous if the compressor generates process steam with a temperature between 100 °C and 450 °C.In In these cases, the aforementioned advantages of the process are particularly evident. This is especially true when the process steam temperature is between 100 °C and 250 °C. A good compromise that allows for efficient use of the steam generation equipment will, in many cases, be achieved with a process steam temperature of at least 200 °C.

[0024] Heating steam can be supplied to the feedwater treatment system for the purpose of, in particular, directly heating the condensate, simply and economically using at least one process steam and / or the raw steam. An external heat source is then not required. This is especially true if the at least one process steam and / or the at least one raw steam is at least partially throttled by a throttle valve to generate the heating steam.

[0025] In In many cases, industrial plants, particularly industrial processes, generate fluids at such low temperatures that the heat they contain is hardly usable. Therefore, it is advantageous to evaporate the liquid phase of the feedwater in the evaporator by heat exchange with a heat source, especially a heat transfer medium, whose temperature is higher than that of the liquid phase in the flash tank and lower than that of the feedwater in the feedwater treatment system. Suitable heat transfer media include the treated feedwater, fluids from biomass plants and / or heat pumps, and / or a geothermal fluid. In principle, waste heat streams, especially those that have not typically been used effectively until now, can be utilized efficiently. A geothermal fluid is defined as one whose heat is supplied primarily through the use of geothermal energy.The geothermal fluid can be either naturally occurring groundwater or a medium subsequently injected from the surface. In both cases, the medium is heated by the underground reservoir and thermally utilized at the surface, where it is cooled. This heating can occur directly as the fluid flows through the rock or indirectly via a closed, separate system. Using a geothermal fluid to evaporate the liquid phase of the feedwater can be particularly advantageous because, although geothermal heat reservoirs are available in many locations, they may only have relatively low temperatures. Otherwise, evaporating the feedwater would only be possible by heating the geothermal fluid itself. However, when using a geothermal fluid, the heat transfer is limited, as the geothermal fluid can only be cooled to approximately the feedwater temperature.

[0026] Suitable geothermal fluids are therefore those that have been heated to a temperature of at least 40 °C, preferably at least 60 °C, using geothermal energy. Compared to other methods, such geothermal fluids can be used very efficiently and economically for the generation of process steam. This is particularly true for geothermal fluids with a temperature of at least 80 °C. Furthermore, due to heat transfer properties, the geothermal fluid is preferably a liquid.

[0027] If required, in addition to the process steam supplied by the at least one compressor, further process steam can be generated in the evaporation unit using at least one steam boiler and / or at least one waste heat boiler. A steam boiler typically comprises an economizer for preheating or heating the feedwater, an evaporator for evaporating the preheated and / or heated feedwater, and a superheater for heating the steam to a desired temperature or at least to a temperature above the saturated steam temperature. In some cases, however, the economizer and / or the superheater can be omitted. The steam boiler is also fired by a combustion system in which fuel is burned to form flue gas. The feedwater is preferably passed in counterflow with the flue gas for preheating, heating, evaporation, and / or superheating.A waste heat boiler may also include an economizer for preheating or heating the feedwater, an evaporator for evaporating the preheated and / or heated feedwater, and a superheater for heating the steam to a desired temperature or at least to a temperature above the saturated steam temperature. However, unlike a steam boiler, a waste heat boiler is not heated with flue gas generated for the purpose of operating the steam boiler, but rather with hot exhaust gas or another hot fluid from an upstream process, which is generated there anyway as a waste heat stream transporting waste heat.

[0028] A portion of the feedwater treated in the feedwater treatment system can be supplied to the steam boiler. However, to utilize the heat of the flue gas, which heats the feedwater in the steam boiler, as fully as possible, it is particularly advantageous to supply a portion of the liquid phase of the feedwater from the flash tank to the steam boiler for evaporation. The liquid phase, cooled in the flash tank, can thus extract more heat from the flue gas in the steam boiler, especially if the flue gas and the liquid phase of the feedwater from the flash tank are circulated in counterflow.

[0029] The process steam generated in the steam boiler can then be combined with the process steam generated in the at least one compressor and then discharged to the consumer device via the discharge device. However, the process steam generated by the steam boiler and the process steam generated by the at least one compressor can also be discharged separately to the consumer device. Each of the aforementioned process steams can also be at least partially throttled and then supplied as heating steam to the feedwater treatment system. It is generally advantageous if the process steam generated in the at least one steam boiler has a temperature of at least 140 °C, preferably at least 150 °C, and particularly at least 160 °C, in order to be used effectively in a consumer device of the industrial plant.Alternatively or additionally, the temperature of the process steam generated in at least one steam boiler is less than 450 °C, preferably less than 250 °C and particularly less than 200 °C, in order to be able to provide the heat to a consumer device in a particularly economical way.

[0030] In a first embodiment of the steam generation unit, which is particularly preferred, the feedwater treatment system has a heating steam supply line for supplying heating steam. This steam can be used to heat and treat the condensate within the feedwater treatment system. Treatment and heating are particularly simple and effective if the feedwater treatment system is designed for direct heating of the condensate with the heating steam. Alternatively or additionally, the feedwater treatment system can be equipped with a vapor outlet through which gases expelled from the condensate in the feedwater treatment system can be discharged. This can occur, particularly when the condensate is directly heated with the heating steam, together with steam, and thus vapors. However, this is not mandatory.

[0031] Regardless, a throttle valve can be assigned to the heating steam supply line to generate heating steam by throttling process steam. This allows a sufficient quantity of heating steam to be supplied to the feedwater treatment system simply and economically.

[0032] To simplify the steam generation system, it may also be advantageous to include a merging system for combining the vapor phase of the feedwater from the flash tank and the raw steam from the evaporator. This allows the vapor phase and the raw steam to be fed together to at least one compressor for the generation of process steam.

[0033] The evaporator can have a condensate feed line for evaporating the liquid phase of the feedwater through heat exchange with the condensate supplied via the feed line. The condensate can then be used simply and effectively for evaporating the liquid phase in the evaporator. Alternatively or additionally, the evaporator can have a feed water feed line for evaporating the liquid phase of the feedwater through heat exchange with the feedwater supplied via the feed line. In this case, the higher temperature of the feedwater compared to the condensate can be utilized. The evaporator can also have a geothermal fluid feed line, as previously defined. The geothermal fluid can then be used to evaporate the liquid phase of the feedwater from the flash tank, provided its temperature is sufficiently higher than that of the liquid phase of the feedwater from the flash tank.

[0034] The use of a geothermal fluid to evaporate the liquid phase of the feedwater can therefore be particularly advantageous because, although geothermal heat reservoirs are available in many locations, they only exhibit relatively low temperature levels. These temperature levels are usually, and often significantly, below 130 °C. Consequently, under economic conditions, these heat reservoirs are either unsuitable or only suitable to a very limited extent for generating process steam using other methods.

[0035] Suitable geothermal fluids are therefore those that have been heated to a temperature of at least 40 °C, preferably at least 60 °C, using geothermal energy. Such geothermal fluids can be used for the generation of process steam very efficiently and economically compared to other methods. This is particularly true for geothermal fluids with a temperature of at least 80 °C. Furthermore, due to heat transfer properties, the geothermal fluid is preferably a liquid.

[0036] The invention will now be explained in more detail with reference to a drawing that illustrates only one embodiment. The drawing shows Fig. 1 an industrial plant for carrying out an industrial process with a steam generating device according to the invention in a schematic view, Fig. 2 the steam generating device made of Fig. 1 in a schematic detailed representation and Fig. 3 an alternative steam generating device in a schematic detailed representation.

[0037] In the Fig. 1 An industrial plant A for carrying out an industrial process P is shown as an example. The industrial plant A shown, and thus preferred, is a paper production plant in which the industrial process P of papermaking is carried out. Alternatively, many other industrial plants A for carrying out different industrial processes P would also be suitable in connection with the invention, the industrial processes P being in particular those that have a considerable heat demand. Papermaking is characterized by a particularly high heat demand, since papermaking is inherently quite energy-intensive. The industrial plant A is partially heated by geothermal energy. A geothermal fluid G is extracted from an underground reservoir W in which the geothermal fluid G has absorbed heat.After thermal utilization in industrial plant A, the geothermal fluid G is returned to the underground reservoir. Thermal utilization refers to the heat transfer in a heat exchanger within industrial plant A. The geothermal fluid G, designated as such because it derives at least some of its heat from geothermal sources, can then be used to heat the industrial process P in industrial plant A. However, it is conceivable that the geothermal fluid could first transfer some of its heat to a transport fluid, which would then be used thermally in industrial plant A instead of the geothermal fluid itself. Thus, when using the transport fluid, the heat is transferred indirectly from the geothermal fluid to industrial plant A.

[0038] In the Fig. 2 A steam generating unit 1 is shown, which supplies the required heat to a consumer unit V of the industrial plant A via a delivery device 2. The heat is used in the form of process steam 3 in the industrial papermaking process P. By using the process steam 3 as a heat source in the corresponding consumer unit V of the industrial process P, the process steam 3 is at least partially condensed, and the resulting condensate 4 is returned to the steam generating unit 1 via a return device 5. The process steam 3 and the condensate 4 are thus circulated, at least substantially, albeit in different states of matter. In the steam generating unit 1 shown, which is preferred in this respect, the delivery device 2 and the return device 5 are designed as a line, specifically a delivery line and a return line.The consumer organization V is located in the . Fig. 2 not shown, as the specific design of the consumer facility V is of no particular importance in this case.

[0039] The condensate 4, returned via the recirculation device 5, is conveyed by a condensate pump 6 to a feedwater treatment unit 7, where it is heated by direct heat exchange with the supplied heating steam 8, in this case from 80 °C to 105 °C. The pressure in the feedwater treatment unit 7 is such that a vapor phase 9 predominates, into which dissolved gases in the condensate, in particular oxygen (O₂) and carbon dioxide (CO₂), are driven off. The vapor phase 9, together with the driven-off gases, is discharged via a vapor vent 10. A suitably treated condensate 4, in the form of feedwater 11, remains in the feedwater treatment unit 7.The feedwater 11 is transferred from the feedwater treatment plant 7 to a flash tank 12, where it is depressurized to such an extent that a portion of the treated feedwater 11 evaporates, thus cooling the feedwater 11. In this way, a vapor phase 13 and a liquid phase 14 of the feedwater 11 are formed in the flash tank 12, both of which have a significantly lower temperature than the treated feedwater 11 in the feedwater treatment plant 7.

[0040] In the illustrated and thus preferred steam generation device 1, a vacuum is created in the flash tank 12 by means of a compressor 15, with the flash tank 12 being located on the suction side of the compressor 15. The pressure in the flash tank 12 is not only lower than the pressure in the feedwater treatment system 7, but also lower than the ambient pressure. It is therefore an absolute pressure of less than 1 bar. The liquid phase 14 of the feedwater 11 remaining in the flash tank 12 is then pumped by means of a feedwater pump 16 through a return line 27 into a steam boiler 17, in which the feedwater 11 is evaporated in a known manner. Of course, two or more steam boilers 17 can also be provided, which are then preferably operated in parallel.

[0041] In the steam boiler 17, a fuel is burned, producing flue gas. The flue gas is conveyed through pipes in which the feedwater 11 flows counter-currently to the flue gas, where it is first heated and then vaporized, and superheated as required. The feedwater 11 is under absolute overpressure, so that in the steam generator 17 it is converted into process steam 18, which can be conveniently used as a heat source for heating the industrial process P in the consumer unit V.

[0042] The liquid phase 14 of the feedwater from the flash tank 12 is transferred to an evaporator 19, in which the liquid phase 14 is evaporated by heat exchange with a heat transfer medium 20, thus forming raw steam 21. In the illustrated and thus preferred pressure generation device, the heat transfer medium 20 is preferably formed from a geothermal fluid, another waste heat stream, feedwater and / or a heat transfer medium from a biomass plant and / or a heat pump.

[0043] The vapor phase 13 of the feedwater 11, formed in the flash tank 12 as a result of the expansion of the treated feedwater 11 via a throttle 22, is combined with the raw steam in a merging unit 28. The steam, composed of the raw steam 21 and the vapor phase 13 of the feedwater 11, is then compressed in the compressor 15, whereby the steam is not only compressed but also heated, so that the compressor forms further process steam 23. In the illustrated and thus preferred pressure-generating device, this further process steam 23 is combined with the process steam 18 from the steam boiler 17 via a merging unit 24. In the illustrated and thus preferred process, the process steam 18 from the steam boiler 17 and the process steam 23 from the compressor 15 have approximately the same pressure. The temperatures can also be approximately the same.A portion of the combined process steam 3 can be fed into the feedwater treatment unit 7 via a throttle 25 and a heating steam supply line 26 as heating steam 8 to heat the condensate 4 therein. The portion of the process steam 3 not required for the formation of heating steam 8 is then discharged to the consumer unit V via the discharge device 2 in the form of a discharge line, before the condensed process steam 3 is later returned as condensate 4 to the steam generation unit 1 via the recirculation device.

[0044] In the Fig. 3 An alternative steam generating unit 30 is shown, which differs from the steam generating unit 1 of the Fig. 2This differs in that the return line 27, the steam boiler 17, the process steam 18 generated in the steam boiler 17, and the merging 24 of the process steam 18 with the process steam 23 generated in the compressor 15 have been omitted. The process steam 3 of the steam generation unit 30 is therefore generated exclusively via the compressor 15, although in principle several compressors 15 could also be provided. In such a case, it could also be provided that the vapor phase 13 of the feedwater 11 from the flash tank 12 is compressed independently in at least one compressor 15 and the raw steam 21 in at least one other compressor 15, even if this would be more complex in terms of equipment, for example, if a very large amount of raw steam 21 and a very large mass flow of vapor phase 13 of the feedwater 11 are generated, or if different pressure levels / steam networks are to be supplied with process steam. Reference symbol list

[0045] 1 Steam generating unit 2 Discharge device 3 Process steam 4 Condensate 5 Recirculation device 6 Condensate pump 7 Feedwater treatment 8 Heating steam 9 Steam phase 10 Vapor discharge 11 Feedwater 12 Flash tank 13 Steam phase 14 Liquid phase 15 Compressor 16 Feedwater pump 17 Steam boiler 18 Process steam boiler 19 Evaporator 20 Heat transfer medium 21 Raw steam 22 Throttle 23 Process steam compressor 24 Combining 25 Throttle 26 Heating steam supply line 27 Return line 28 Combining 30 Steam generating unit Aindustrial plant GGeothermal fluid PIndustrial process VConsumer facility WWothere reservoir

Claims

1. Method for generating process steam (3) using condensate (4) that is returned in the form of feed water (11), - in which the process steam (3) is supplied to a consumer device (V) to form condensate (4) by at least partial condensation of the process steam (3), - in which the condensate (4) is supplied from the consumer device (V) to a feed water treatment unit (7) for treatment, - in which feed water (11) from the feed water treatment unit (7) is separated into a vapor phase (13) and a liquid phase (14) in a flash tank (12), - in which the liquid phase (14) of the feed water (11) is evaporated in an evaporator (19) to form a raw steam (21), and - in which the vapor phase (13) of the feed water (11) and the raw steam (21) are compressed in at least one compressor (15) to form process steam (3).

2. Method according to claim 1, - in which the condensate (4) is at least partially degassed in the feed water treatment (7) to form feed water (11), in particular by separating oxygen (O2) and / or carbon dioxide (CO2), and - in which, preferably, the condensate (4) is fed to the feed water treatment unit (7) together with heating steam (8) for, in particular, direct heating of the condensate (4).

3. Method according to claim 1 or 2, - in which the condensate (4) is supplied to the feed water treatment unit (7) at a temperature between 60 °C and 100 °C, preferably between 70 °C and 80 °C, in particular at least substantially 80 °C, and / or - in which the condensate (4) is degassed in the feed water treatment unit (7) at a pressure between 1 bar and 2 bar, preferably between 1.1 and 1.5 bar, in particular of at least substantially 1.2 bar, and / or at a temperature above 100 °C, preferably between 102 °C and 108 °C, in particular at least substantially 105 °C.

4. Method according to one of claims 1 to 3, - in which the flash tank (12) is operated at a pressure between 0.07 bar and 0.9 bar, preferably between 0.12 bar and 0.8 bar, in particular at least substantially 0.2 bar or 0.6 bar, and / or - in which the flash tank (12) is operated at a temperature between 40 °C and 96 °C, preferably between 50 °C and 93.5 °C, in particular at least substantially 60 °C or 85.9 °C.

5. Method according to one of claims 1 to 4, - in which the compressor (15) generates a negative pressure in the flash tank, at least in comparison to the pressure in the feed water treatment unit (7) and / or - in which the at least one compressor (15) generates process steam (3) with a temperature between 100 °C and 450 °C, preferably between 100 °C and 250 °C, in particular at least substantially 200 °C.

6. Method according to one of claims 1 to 5, - in which the heating steam (8) of the feed water treatment unit (7) is provided at least partially by a process steam (3) and / or raw steam (21) in particular throttled via a throttle (25).

7. Method according to one of claims 1 to 6, - in which the liquid phase (14) of the feed water (11) is evaporated in the evaporator (19) by heat exchange with a heat transfer medium (20), in particular feed water (11), heat flows from biomass plants and / or heat pumps, waste heat flows, and / or geothermal fluid (G), and - wherein, preferably, the geothermal fluid (G) has a temperature of at least 40 °C, preferably at least 60 °C, in particular at least 80 °C.

8. Method according to one of claims 1 to 7, - in which the feed water (11), in particular the liquid phase (14) of the feed water (11) from the flash tank (12), is partially supplied to at least one steam boiler (17) and evaporated in the at least one steam boiler (17) to form process steam (3), and - in which, preferably, the process steam (3) from the at least one steam boiler (17) and the process steam (3) from the at least one compressor (15) are at least partially combined and delivered to the consumer device (V) via the delivery device (2).

9. Steam generation device (1) for generating process steam (3) using condensate (4) that is returned in the form of feed water (11), preferably using a method according to one of claims 1 to 8, with a flash tank (12) for separating the feed water (11) into a vapor phase (13) and a liquid phase (14), with an evaporator (19) for evaporating the liquid phase (14) of the feed water (11) to form raw steam (21), with at least one compressor (15) for compressing the vapor phase (13) of the feed water (11) and the raw steam (21) to form process steam (3), with a delivery device (2) for supplying the process steam (3) to a consumer device (V) for forming condensate (4) by condensation of the process steam (3), with a return device (5) for supplying the condensate (4), and with a feed water treatment unit (7) for treating the condensate (4) to form the feed water (11).

10. Steam generation device according to claim 9, characterized in that the feed water treatment unit (7) comprises a heating steam supply line (26) for, in particular, directly heating the condensate (4) and / or a vapor discharge line (10) for discharging gas expelled from the condensate (4), and that, preferably, the heating steam supply line (26) is associated with a throttle (25) for forming heating steam (8) by throttling process steam (3).

11. Steam generation device according to claim 9 or 10, characterized in that a merging (28) is provided for the vapor phase (13) of the feed water (11) and the raw steam (21), and that, preferably, at least one compressor (15) is provided for jointly compressing the vapor phase (13) of the feed water (11) and the raw steam (21) after the merging (28).

12. Steam generation device according to one of claims 9 to 11, characterized in that the evaporator (19) comprises a supply line for condensate (4) for evaporating the liquid phase (14) of the feed water (11), and the evaporator (19) is configured to evaporate the liquid phase (14) of the feedwater (11) by heat exchange with the condensate (4) supplied via the supply line, and / or that the evaporator (19) comprises a supply line for feed water (11) for evaporating the liquid phase (14) of the feed water (11), and the evaporator (19) is configured to evaporate the liquid phase (14) of the feedwater (11) by heat exchange with the feedwater (11) supplied via the supply line, and / or that the evaporator (19) comprises a supply line for geothermal fluid (G) for evaporating the liquid phase (14) of the feed water (11), and the evaporator (19) is configured to evaporate the liquid phase (14) of the feedwater (11) by heat exchange with the geothermal fluid (G) supplied via the supply line.

13. Steam generation device according to one of claims 9 to 12, characterized in that the geothermal fluid (G) has a temperature of at least 40 °C, preferably at least 60 °C, in particular at least 80 °C.