Steam generating equipment and method for its operation

Abstract

The present invention relates to a steam generating system (1) comprising at least one steam generator (2) and a compressor (4) having a plurality of successive compressor stages (10, 11, 12), wherein a thermal energy storage system (5) is provided after the plurality of compressor stages (10, 11, 12), particularly after each compressor stage (10, 11, 12), to selectively extract steam at a plurality of different pressure levels from the compressor (4), store the extracted steam at the plurality of different pressure levels, and selectively supply the stored steam to the compressor (4) at an appropriate pressure level before and / or after the plurality of compressor stages (10, 11, 12), characterized in that the thermal energy storage system (5) selectively supplies the stored steam at an appropriate pressure level to the compressor (4) after the last compressor stage (12). The present invention also relates to a method for operating such a steam generating system (1).

Description

Technical Field

[0003]

[0001] The present invention relates to steam generation equipment comprising at least one steam generator and a compressor having a plurality of successive compressor stages. Further, the present invention relates to a method for operating such steam equipment.

[0002] In various industrial processes, process steam at different pressure levels is required. Examples of such industries are the paper, food and chemical industries, or oil and gas refineries.

[0003] For the generation of process steam at medium and high pressure levels, steam generation equipment of the type mentioned at the beginning is used, in which the steam generated in the steam generator is compressed to the desired pressure level in the compressor. In recent years, the compressors of such steam generation equipment have been configured or arranged in multiple stages, and the steam is withdrawn behind each individual compressor stage as accurately as possible, i.e., at the pressure required from the perspective of the process. The mass flow rate requirements of the individual compressor stages may be different and may vary independently of each other. Thereby, for each compressor stage, different mass flow rate requirements that vary independently of each other occur. Against this background, in individual or multiple compressor stages, there is a possibility of falling below or exceeding an acceptable mass flow rate, which should be avoided. When the mass flow rate is too low and the pressure ratio is too high, when reaching the so-called surge limit, the flow may separate from the compressor blades, thereby interrupting the conveying process. When the mass flow rate is too high and the pressure ratio is too low, the so-called suction limit is reached, which defines the maximum possible throughput of the compressor stage. Falling below or exceeding the surge limit or the suction limit causes the compressor to shut down, thereby making it impossible to operate the process that requires steam any longer.

[0004] Previously, when the load requirements were not met, the steam was either released or extracted by the condenser. However, discarding steam in this way is noisy and energy-inefficient, and should be avoided. Water should also be conserved. To avoid falling below the surge limit, the steam can be recirculated around the compressor. However, this is not energy-efficient.

[0005] Based on this prior art, the object of the present invention is to create a steam generating apparatus of the type described above having an improved structure, and a more efficient method for operating such a steam generating apparatus.

[0006] To solve this problem, the present invention creates the type of steam generating equipment described at the beginning, characterized in that a thermal energy storage system is provided, after a plurality of compressor stages, particularly after each compressor stage, which is designed to selectively extract steam at a plurality of different pressure levels from the compressor, store the extracted steam at a plurality of different pressure levels, and selectively supply the stored steam to the compressor at an appropriate pressure level before and / or after the plurality of compressor stages, and the thermal energy storage system is designed to selectively supply the stored steam at an appropriate pressure level to the compressor after the last compressor stage. Steam storage in the thermal energy storage can be carried out in vapor and / or liquid form. Therefore, when “steam storage” is referred to below, it does not mean in aggregate form unless explicitly noted. Furthermore, the thermal energy storage may be designed to allow water or steam to be supplied to and extracted from the thermal energy storage from a separate source, for example, to replenish the energy storage or to extract excess water or excess steam for use elsewhere as needed.

[0007] The thermal energy storage system according to the present invention allows for the optimization, adjustment, or regulation of the mass flow rate through each individual compressor stage as needed. Specifically, when the mass flow rate from the steam generator or preceding compressor stage is insufficient, the energy storage system can be incorporated to make the correct mass flow rate at the correct pressure available according to the requirements of the consumers assigned to each compressor stage. Furthermore, when the mass flow rate from the steam generator or preceding compressor stage is excessive, the excess steam can be discharged and stored in the thermal energy storage system. In this way, each compressor stage can be kept within its operating range without requiring shutdown or steam recirculation. Additionally, the steam volume can be adapted to optimize the mass flow rate and increase the efficiency of the steam generation equipment. This is possible because the efficiency of a compressor stage depends on the mass flow rate and differential pressure of the compressor stage. The adjustment or regulation of the mass flow rate through each individual compressor stage is, of course, performed using appropriately formed evaluation and control units, suitable sensors that specifically detect the mass flow rate in the pipeline, particularly in the pipeline to consumers, and adjustment devices such as valves and flaps.

[0008] The thermal energy storage system is designed to selectively supply stored steam at an appropriate pressure level to the compressor after the final compressor stage. In this way, even if the steam generated by the upstream steam generator is insufficient, for example during the startup phase of the steam generation equipment, sufficient steam can be made available at the compressor outlet.

[0009] According to the present invention, a thermal energy storage system may have a loose storage unit. Such a loose storage unit allows for direct steam injection without the need for intermediate circuits and heat exchangers connected thereto, as well as additional pumps, thereby resulting in an overall inexpensive structure.

[0010] Alternatively or additionally, the thermal energy storage system may have at least one feedwater container having a thermal degassing section. Such a feedwater container requires steam to ensure degassing from the feedwater. This steam supply provides heating to the feedwater, which normally exists as a boiling liquid. The feedwater container is also designed to fit a specific operating range, thereby allowing flexibility with respect to the volume and pressure / temperature. If the compressor stages exceed the suction limit, the amount of steam can be reduced by reducing or shutting down the steam supply to the feedwater container, thereby bringing the corresponding compressor stages back into their operating range. If the amount of steam across the compressor stages is too low, the compressor stages can be stabilized by increasing the steam flow rate to the feedwater container. Overall, this reduces manufacturing costs in terms of equipment, and consequently, materials and energy. Furthermore, space requirements are reduced, thereby increasing the feasibility of retrofitting the thermal energy storage system according to the present invention into existing, confined spaces.

[0011] According to further embodiments of the present invention, the thermal energy storage system may optionally or additionally include a condensate container. The condensate container can increase the amount of steam across the compressor stage by heating the condensate without the need to release steam. This can reduce water losses in the equipment.

[0012] Alternatively or additionally, the thermal energy storage system according to the present invention may include a large water boiler. Similar to a feedwater container, a water tank within the large water boiler can be switched on or off depending on the operating state of the compressor stage, and here it can be used particularly as a storage for preheating in the heat retention mode.

[0013] According to one embodiment of the present invention, a thermal energy storage system has at least one heat source designed to heat the stored steam. Such a heat source makes it possible to bring the steam stored in the energy storage system to a desired temperature / pressure level. The at least one heat source is preferably an electrically operated heat source such as an electrode boiler or heating rod, thereby enabling optimal utilization of the fluctuating supply of electricity from renewable energy sources from the perspective of the heat generator. This facilitates its integration into the power grid by making it possible to match the electricity usage of individual purchasers to the fluctuating supply of electricity from renewable energy sources. Therefore, for example, when the steam generator is not yet fully started up, at least one heat source can be used to directly supply a steam source via the thermal energy storage system when the compressor is started up. Furthermore, if the steam volume requirement increases, an additional heat source can be used to replenish the required steam or fill the thermal energy storage system.

[0014] Advantageously, at least one steam generator is a high-temperature heat pump, which is powered, for example, by the waste heat of one or more processes that are supplied with steam through the steam generation equipment, and / or by the waste heat of external processes. However, it should be noted that not only such high-temperature heat pumps, but also additional steam generators that can be used together with or as replacements for high-temperature heat pumps can be used. Compared to conventional steam generators, high-temperature heat pumps have the advantage of being able to operate in a way that is, in some cases, completely CO2 neutral by utilizing existing waste heat and electricity from renewable energy.

[0015] Advantageously, the thermal energy storage system is designed to supply stored steam at an appropriate pressure level to the evaporator of a high-temperature heat pump. Thus, the steam stored in the thermal energy storage system can be used, for example, to start the heat pump when the process is not yet available as a heat source.

[0016] To solve the problems mentioned at the beginning, the present invention further provides a method for operating a steam generating system comprising at least one steam generator and a compressor having a plurality of consecutive compressor stages, and more particularly a method for operating a steam generating system according to the present invention, wherein the operating state of each compressor stage is monitored, and when a compressor stage approaches its individual surge limit, the steam mass flow rate immediately behind that compressor stage is withdrawn until it reaches a predetermined operating state, the withdrawn steam is stored in a thermal energy storage system, and when a compressor stage approaches its individual suction limit, a steam mass flow rate at an appropriate pressure level is supplied from the thermal energy storage system immediately behind that compressor stage until it reaches a predetermined operating state. In particular, when the amount of steam generated by an upstream steam generator is too small, such as during the startup phase of the steam generating system, a steam mass flow rate at an appropriate pressure level is selectively supplied from the thermal energy storage system after the last compressor stage.

[0017] According to one embodiment of the present invention, steam stored in a thermal energy storage system is selectively heated by at least one heat source.

[0018] Advantageously, at least one of the steam generators is a high-temperature heat pump, and in particular, its evaporator is selectively operated by steam stored in a thermal energy storage system.

[0019] Further features and advantages of the present invention will become apparent based on the following description with reference to the accompanying drawings. [Brief explanation of the drawing]

[0020] [Figure 1] This is a schematic diagram of a steam generation facility according to one embodiment of the present invention. [Figure 2] This is a schematic diagram of a steam generation facility according to a further embodiment of the present invention. [Modes for carrying out the invention]

[0021] From this point forward, the same reference number will represent the same or similar component.

[0022] Figure 1 shows a steam generation system 1 according to one embodiment of the present invention, comprising, as its main components, at least one steam generator 2, a compressor 4 connected to the steam generator 2 via a pipeline 3, a thermal energy storage system 5, and an evaluation unit and a control unit 6. The compressor 4 has a plurality of consecutive compressor stages 10, 11, and 12 connected by pipelines 7, 8, and 9, which compress the steam produced by the steam generator 2 to different pressure levels. In the illustrated example, the steam produced in the steam generator 2 is supplied to the compressor 4, and thus to the first compressor stage 10, at a pressure of 1.6 bar, from which this steam is further compressed to pressures of 2.8 bar, 5.0 bar, and 9.0 bar in the individual compressor stages 10, 11, and 12. It should be clear that the number of compressor stages and the pressure of each can be fundamentally variable. From pipelines 3, 7, and 9, i.e., between the steam generator 2 and the compressor 4, and between each compressor stage 10, 11, and 12, and from pipeline 13 coming from the last compressor stage 12, pipelines 14, 15, 16, and 17 branch off, through which steam with corresponding pressure levels is supplied to various consumers 18, 19, 20, and 21. From pipelines 7 and 9 between the compressor stages 10, 11, and 12, and from pipeline 13 coming from the last compressor stage 12, further pipelines 22, 23, and 24 branch off, which are connected to thermal energy storage units 5. Thermal energy storage units 5 are designed to store steam at different pressure levels. Alternatively, although not shown here, multiple thermal energy storage units may be provided for this purpose. Further conduits 25, 26, and 27 return from the thermal energy storage unit 5 to conduits 3 and 7, and optionally, further conduit 28, shown here by a dashed line, connects to conduit 13. Conduits 22, 23, 24, 25, 26, 27, and 28 are each equipped with a control device 29, which can be driven by motors via an evaluation unit and a control unit 6.Furthermore, in this embodiment, all pipelines 7, 9, 13, 14, 15, 16, 17, 22, 23, 24, 25, 26, 27, and 28 are equipped with sensors 30 that detect the steam mass flow rate delivered through pipelines 7, 9, 13, 14, 15, 16, 17, 22, 23, 24, 25, 26, 27, and 28, and transmit the detected measurements to the evaluation unit and control unit 6. It should be clear that, since calculations can also be made based on measurements from sensors with essentially lower mass flow rates, additional adjustment devices may be provided in addition to the adjustment device 29 described, and / or some of the sensors 30 may be omitted. The thermal energy storage system 5 may have at least one loose storage, and / or at least one feedwater container having a thermal degassing section, and / or at least one condensate container, and / or at least one large water boiler. The advantages of each have already been described at the beginning, so to avoid repetition, they will not be mentioned again here. The thermal energy storage system 5 may have one or more additional heating sources 31, such as electric heating sources, for heating the steam stored therein.

[0023] During the operation of the steam generator 1, consumers 18, 19, 20, and 21 have fluctuating demands for steam mass flow rates at different pressure levels, which should be met by the steam generated by the steam generator 2. Here, the evaluation unit and control unit 6 balance the mass flow rates of each individual compressor stage 10, 11, and 12 based on measurements provided by the sensor 30 and compare these to the corresponding operating ranges of the compressor stages 10, 11, and 12 stored in the evaluation unit and control unit 6. If it is found that a predefined limit has been exceeded in the direction of the surge limit or suction limit of each compressor stage 10, 11, and 12, measures are taken to discharge the steam through one or more pipelines 22, 23, and 24 and store it in the thermal energy storage 5, or to supply steam from the thermal energy storage 5 through one or more pipelines 25, 26, and 27. Here, when compressor stages 10, 11, and 12 approach their individual pump limits, the steam mass flow rate is withdrawn immediately behind these compressor stages 10, 11, and 12 until it reaches the predetermined operating state, and the withdrawn steam is stored in the thermal energy storage unit 5. When compressor stages 10, 11, and 12 approach their individual suction limits, the steam mass flow rate at the appropriate pressure level is supplied from the thermal energy storage unit 5 immediately behind these compressor stages 10, 11, and 12 until it reaches the predetermined operating state. In this way, the shutdown of the corresponding compressor stages 10, 11, and 12 can be reliably prevented. Preferably, each mass flow rate is kept at an optimal level that optimizes the efficiency of the steam generating equipment 1.

[0024] When starting up the steam generation equipment 1, steam can also be drawn from the thermal energy storage 5 as long as the steam generator 2 does not produce enough steam, thereby minimizing the startup time. If consumers 18, 19, 20, and 21 temporarily require more steam than the steam generator 2 can produce, this additional mass flow rate can also be supplied via the thermal energy storage 5. Similarly, control can be made in response to electricity prices, fuel prices, and / or CO2 prices. For example, when electricity prices are low or even negative, especially when there is a large supply of electricity from renewable energy sources, more steam can be produced in the steam generator 2 than is required by consumers 18, 19, 20, and 21, and the excess steam can then be stored in the thermal energy storage 5. Then, during periods of high electricity prices, steam can be supplied from the thermal energy storage 5. Naturally, it is also possible to install multiple different steam generators 2, for example, steam boiler steam generators and / or CHP steam generators and / or solar and / or geothermal steam generators, thereby enabling reliable and inexpensive steam generation even during periods of high energy prices. The steam generation equipment 1 may also have additional electrical or thermomechanical energy storage, with or without power reconversion (Rueckverstromung).

[0025] Figure 2 shows a steam generator 1 according to a further embodiment of the present invention, the structure and function being substantially the same as the steam generator 1 shown in Figure 1 and described earlier. However, in the case of the steam generator 1 illustrated in Figure 2, the steam generator 2 is formed by a high-temperature heat pump having an evaporator 32, a compressor 33, a condenser 34, and a throttle 35, as is known. Here, the evaporator 32 is supplied with process waste heat via a pipeline 36 and / or energy necessary to evaporate the refrigerant via a pipeline 37 connected to a thermal energy storage 5. The feedwater supplied via the pipeline is evaporated in the condenser 34 and supplied to the compressor 4.

[0026] Although the present invention has been illustrated and described in more detail by preferred embodiments, the present invention is not limited to the disclosed examples, and those skilled in the art can derive other modified forms without departing from the protection scope of the present invention.

[0027] Regardless of the grammatical gender of a particular term, personal pronouns having the identity of male, female, or other genders are included.

Description of Reference Numerals

[0028] 1 Steam generation facility 2 Steam generator 3 Pipeline 4 Compressor 5 Thermal energy storage system 6 Evaluation unit and control unit 7 Pipeline 8 Pipeline 9 Pipeline 10 Compressor stage 11 Compressor stage 12 Compressor stage 13 Pipeline 14 Pipeline 15 Pipeline 16 Pipeline 17 Pipeline 18 Consumer 19 Consumer 20 Consumer 21 Consumer 22 Pipeline 23 Pipeline 24 Pipeline 25 Pipeline 26 Pipeline 27 Pipeline 28 Pipeline 29 Adjustment device 30 Sensor 31 Heat source 32 Evaporator 33 Compressor 34 Condenser 35 Throttle 36 Pipeline 37 Pipeline

Claims

1. A steam generating apparatus (1) comprising at least one steam generator (2) and a compressor (4) having a plurality of consecutive compressor stages (10, 11, 12), A thermal energy storage system (5) is provided, after a plurality of compressor stages (10, 11, 12), particularly after each compressor stage (10, 11, 12), which is designed to selectively extract steam at multiple different pressure levels from the compressor (4), store the extracted steam at multiple different pressure levels, and selectively supply the stored steam to the compressor (4) at appropriate pressure levels before and / or after the plurality of compressor stages (10, 11, 12). The thermal energy storage system (5) is designed to selectively supply stored steam at an appropriate pressure level to the compressor (4) after the final compressor stage (12). A steam generating apparatus (1) characterized by the following:

2. The steam generating apparatus (1) according to claim 1, characterized in that the thermal energy storage system (5) has at least one loose storage body.

3. The steam generating equipment (1) according to claim 1 or 2, characterized in that the thermal energy storage system (5) has at least one water supply container having a thermal degassing section.

4. The steam generating equipment (1) according to any one of claims 1 to 3, characterized in that the thermal energy storage system (5) has at least one condensate container.

5. The steam generating equipment (1) according to any one of claims 1 to 4, characterized in that the thermal energy storage system (5) has at least one large water boiler.

6. The steam generating equipment (1) according to any one of claims 1 to 5, characterized in that the thermal energy storage system (5) has at least one heat source (31) designed to heat the stored steam.

7. The steam generating equipment (1) according to any one of claims 1 to 6, characterized in that the at least one steam generator (2) is a high-temperature heat pump.

8. The steam generating equipment (1) according to claim 7, characterized in that the thermal energy storage system (5) is designed to supply stored steam at an appropriate pressure level to the evaporator (32) of the high-temperature heat pump.

9. A method for operating a steam generating system (1) comprising at least one steam generator (2) and a compressor (4) having a plurality of consecutive compressor stages (10, 11, 12), The operating status of each compressor stage (10, 11, 12) is monitored. When the compressor stages (10, 11, 12) approach their respective surge limits, steam mass flow rate is withdrawn immediately behind the compressor stages (10, 11, 12) until it reaches the predetermined operating state, and the withdrawn steam is stored in the thermal energy storage system (5). As the compressor stages (10, 11, 12) approach their individual suction limits, the thermal energy storage system (5) supplies a steam mass flow rate at an appropriate pressure level immediately before these compressor stages (10, 11, 12) until the predetermined operating state is reached. After the final compressor stage (12), a steam mass flow rate at an appropriate pressure level is selectively supplied from the thermal energy storage system (5). method.

10. The method according to claim 9, wherein the steam stored in the thermal energy storage system (5) is selectively heated via at least one heat source (31).

11. The method according to claim 9 or 10, wherein the at least one steam generator (2) is a high-temperature heat pump, and its evaporator (32) is selectively operated by steam stored in the thermal energy storage system (5).

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