Method for operating a gas-turbine plant, gas-turbine plant, computer program product and computer-readable medium

Abstract

The invention relates to a method, in particular a computer-assisted method, for operating a gas-turbine plant, wherein the gas-turbine plant can be operated at times at different load levels, wherein a limit value is set for an average emission value based on a measurement period, in particular an emission concentration or an emission rate, of nitrogen oxide, said limit value corresponding to a limit value for the nitrogen oxide emissions over the measurement period, wherein operating parameters are selected such that, during operation at a low load level, the nitrogen oxide emissions fall below the limit value for the average emission value and, during operation at a high load level, the nitrogen oxide emissions at least temporarily exceed the limit value for the average emission value.

Description

[0001] 2024PF00177 1

[0002] Description

[0003] Method for operating a gas turbine plant, gas turbine plant, computer program product and computer-readable medium

[0004] The present invention relates to a method, in particular a computer-aided method, for operating a gas turbine plant. Furthermore, the invention relates to a gas turbine plant, a computer program product, and a computer-readable medium.

[0005] Gas turbines play an important role in the energy transition. Due to their flexibility, they are able to react quickly to fluctuations in electricity demand.

[0006] When operating a gas turbine plant, certain emission limits must be observed. These may be stipulated by laws, regulations, directives, or similar provisions, or they may result from emissions trading. In particular, limits for nitrogen oxide emissions must be met. Selective catalytic reduction (SCR) catalysts are frequently used to reduce nitrogen oxide emissions. These catalysts undergo selective catalytic reduction, which reduces the nitrogen oxides in the turbine's exhaust gas. This selective catalytic reaction largely suppresses undesirable reactions. In practice, ammonia is used for selective catalytic reduction and is added to the exhaust gas.

[0007] In many countries, various limits must be observed for nitrogen oxide emissions and ammonia emissions. There are usually annual limits, which correspond to the maximum permissible nitrogen oxide emissions over a calendar year. In addition, there are also daily limits, which are usually higher than the annual limit. This means that the average daily emissions permitted by the annual limit may be exceeded on individual days.

[0008] The amount of ammonia supplied to the SCR catalyst is generally set so that the annual limit is met at all times and in all operating conditions. This means that at any given time, nitrogen oxide emissions and ammonia emissions are below the permitted limits for the calendar year.

[0009] Gas turbine plants are not typically operated at full load continuously. Rather, there are periods when the gas turbine plants operate at a low load level and periods when they operate at a high load level. To remain below a certain level of nitrogen oxide emissions, a significantly smaller amount of ammonia is required at a low load level than at a high load level. If a gas turbine plant is operated in such a way that an emission value corresponding to the permissible annual limit is not exceeded at any given time, then a relatively large amount of ammonia is required during periods of high load level.

[0010] Against this background, the object of the present invention is to provide an alternative method for operating a gas turbine plant and a gas turbine plant itself, which in particular reduces the consumption of auxiliary materials, for example ammonia. 2024PF00177 3

[0011] This problem is solved by a method, in particular a computer-aided method, for operating a gas turbine plant, wherein the gas turbine plant can be operated phasewise at different load levels, wherein a limit value for an average emission value related to a recording period, in particular an emission concentration or emission rate, of nitrogen oxide is / is set, which corresponds to a limit value for the nitrogen oxide emissions over the recording period, characterized in that operating parameters are selected such that, during operation at a low load level, the nitrogen oxide emissions fall below the limit value for the average emission value and, during operation at a high load level, the nitrogen oxide emissions at least temporarily exceed the limit value for the average emission value.

[0012] The invention is based on the idea of ​​remaining below the limit for average emissions during periods of low load, thus creating a reserve of permissible nitrogen oxide emissions. At low load, only a comparatively small amount of ammonia is required. If the system is then operated during periods of high load, this reserve of nitrogen oxide emissions can be practically depleted compared to the limit, and the average emission value can be temporarily exceeded. This allows ammonia consumption to be significantly reduced during periods of high load.

[0013] The average emission value can be an emission rate. The emission rate can be determined, for example, by dividing the limit for the maximum permissible amount of nitrogen oxide emitted over the monitoring period by the duration of the monitoring period. 2024PF00177 4

[0014] Alternatively, the average emission value can be an emission concentration. In this case, the emission value preferably corresponds to a concentration of nitrogen oxides, for example, in the exhaust gas. The emission concentration can be an absolute emission concentration, which is expressed, for example, in g / m³. 3 is specified, or a time-related emission concentration, which is e.g. in g / (m³). 3 is specified as xs) or a comparable unit.

[0015] Nitrogen oxide emissions can refer to an absolute quantity of emitted nitrogen oxides. Nitrogen oxide emissions can also refer to a concentration, particularly in relation to the exhaust gas.

[0016] Nitrogen oxide emissions can include NO and / or NO2.

[0017] Phases with a high load level can be defined in particular as those phases in which the gas turbine plant is operated with a load that corresponds to at least 60%, in particular at least 70%, preferably at least 80%, of the maximum rated load. Phases with a low load level, which can also be referred to as partial load, can be characterized in that the load corresponds to at most 70%, in particular at most 60%, preferably at most 50%, of the maximum rated load of the gas turbine plant.

[0018] In a further embodiment, operating parameters can be selected such that the limit value for nitrogen oxide emissions is not exceeded over the recording period. This means that over the recording period, for example, a calendar year, the gas turbine plant remains below the maximum permissible nitrogen oxide emissions for that period. Preferably, the operating parameters are selected such that at every point in time within the 2024PF00177 5

[0019] Recording period, i.e., in the already expired section of the recording period, the nitrogen oxide emissions are below the proportionate permissible emissions defined by the limit value, relating to the period.

[0020] In a further refinement, operating parameters can be selected such that, in a sub-section, particularly in the first sub-section, of the recording period, the limit value for the average nitrogen oxide emission level is not exceeded, regardless of the load level. This refinement is based on the consideration of ensuring that nitrogen oxide emissions do not exceed the permissible limit value for the portion of the recording period that has already elapsed at any point during the recording period. For example, if the gas turbine plant is operated at a high load level at the beginning of a recording period, the nitrogen oxide emissions can remain below the limit value, even if this requires a relatively high ammonia consumption, since at the beginning of a recording period there is no reserve of nitrogen oxide emissions from a limit value undercutting during operation at a low load level.

[0021] In concrete terms, the recording period can be 30 minutes, one hour, 3 hours, 6 hours, 12 hours, 24 hours, 1 week, 1 month, 2 months, 3 months, 6 months or one year.

[0022] The recording period usually depends on legal regulations or the respective permit for the gas turbine plant.

[0023] At least one additional limit value for nitrogen oxide emissions over a partial period of the recording period can be set. The operating parameters 2024PF00177 6 of the gas turbine plant can be selected such that the nitrogen oxide emissions do not exceed the respective additional limit value over the respective partial period. Specifically, the partial period can have a duration of 30 minutes, 1 hour, 3 hours, 6 hours, 12 hours, 24 hours, 1 week, 10 days, 2 weeks, or 1 month.

[0024] This design of the procedure takes into account the fact that, in addition to a limit value for the entire recording period, there are often also limit values ​​for partial periods. For example, a recording period of one year, such as a calendar year, and daily limit values, i.e., partial periods of one day, are common. Therefore, the plant operator must ensure that both the maximum permissible nitrogen oxide emissions over the recording period and the maximum permissible nitrogen oxide emissions for each partial period are complied with.

[0025] It is possible that several limit values ​​for nitrogen oxide emissions are / will be set for different periods. Therefore, there may not just be one limit value for a single period, but several different limit values ​​for nitrogen oxide emissions across different periods.

[0026] The recording period, or at least one sub-period, can be fixed or rolling periods. This means that the recording period is either a fixed period, for example, a calendar year, or it shifts continuously, for example, the previous year or the most recent 365 days. 2024PF00177 7

[0027] In a further embodiment, the gas turbine plant can include an SCR catalyst. An auxiliary substance, in particular ammonia, can be added to this catalyst. The addition of ammonia (NH3) and its mixing with exhaust gas can trigger a reaction that produces water and nitrogen as products.

[0028] One operating parameter that can be adjusted to control nitrogen oxide emissions is the amount of auxiliary material supplied. This design is based on the consideration that the amount of auxiliary material, for example ammonia, supplied to the SCR catalyst influences nitrogen oxide emissions. Preferably, the amount of auxiliary material is increased when nitrogen oxide emissions are to be reduced. The method according to the invention leads to an overall reduction in ammonia consumption.

[0029] The problem underlying the invention is further solved by a gas turbine plant with means adapted to carry out the process as described above. Specifically, the gas turbine plant can include an SCR catalyst, wherein the SCR catalyst in particular comprises means for supplying an auxiliary substance, preferably ammonia. These can include means for controlling the amount of auxiliary substance to be supplied.

[0030] In a further embodiment, the gas turbine plant can include a control device for carrying out the previously described method. In other words, the means for carrying out the method according to the invention can include a control device.

[0031] Furthermore, the gas turbine plant may have measuring equipment for recording nitrogen oxide emissions. 2024PF00177 8

[0032] The gas turbine plant can be designed as a combined cycle power plant (CCPP). In other words, the gas turbine plant can be a combined cycle gas turbine (CCGT). Such a plant is based on the idea that the hot exhaust gas stream from a gas turbine can be used to generate steam. The generated steam can then drive a steam turbine, for example, with different pressure stages. Preferably, the gas turbine and the steam turbine simultaneously drive a generator via a common shaft.

[0033] The problem underlying the invention is further solved by a computer program product comprising commands that cause the gas turbine plant according to the invention to carry out the process as described above.

[0034] Furthermore, the invention creates a computer-readable medium on which the computer program product is stored as described above.

[0035] For further details of the invention, reference is made to the dependent claims and to the description of an exemplary embodiment with reference to the accompanying drawing. The drawing shows:

[0036] Figure 1 shows a graph of the nitrogen oxide emission concentration over time when using the inventive method for operating a gas turbine plant.

[0037] Figure 1 schematically shows the course of nitrogen oxide emissions during the operation of a gas turbine plant, which is designed as a combined cycle gas turbine (CCGT) plant and contains an SCR catalyst. Ammonia can be fed to the SCR catalyst as an auxiliary substance to reduce nitrogen oxide emissions. 2024PF00177 9

[0038] The gas turbine plant can be operated at different load levels in phases. A limit value 1 for an average emission concentration of nitrogen oxides, related to a measurement period T, is set.

[0039] In the graph of Figure 1, where the horizontal axis represents time T and the vertical axis represents an emission concentration E / t, specifically related to time, for the nitrogen oxide emission of the gas turbine plant, the limit value 1 is shown as a dashed horizontal line. This corresponds to the limit value for nitrogen oxide emissions over the monitoring period T, which in this case is one year. In other words, it corresponds to the maximum permissible nitrogen oxide emissions over the monitoring period.

[0040] In addition to the limit value for nitrogen oxide emissions for the recording period T, there is a further limit value 2 for the average nitrogen oxide emissions over a sub-period of the recording period T. Figure 1 schematically shows eight sub-periods, which together constitute the recording period T. The further limit value 2 for nitrogen oxide emissions over the sub-periods is higher than limit value 1 and is indicated by a dashed line. The division into eight sub-periods serves only as a schematic representation. Sub-periods of 24 hours or other durations are also possible.

[0041] Solid line 3 shows the nitrogen oxide emission concentration from the gas turbine plant. In an initial phase, which extends over approximately the first two periods, the gas turbine plant operates at a low load level. This results in lower nitrogen oxide emissions than the limit value 1 for the average emission over the measurement period.

[0042] The permissible emission concentration would be [missing information]. The amount of nitrogen oxide emissions "saved" compared to this is represented by the shaded area.

[0043] The third part of the time period then involves a phase with high load levels. During this period, higher quantities of nitrogen oxides are emitted than would actually be permitted by limit value 1. The amount of nitrogen oxides exceeding limit value 1 is represented by the oppositely shaded area. The same load change then repeats itself once more over a slightly longer period.

[0044] Because the limit value 1 is significantly undercut at low load levels, exceedances during periods of high load can be accepted. This allows for a significant reduction in ammonia consumption. Simultaneously, it is ensured that the maximum permissible nitrogen oxide emissions are not exceeded over the entire monitoring period. This is achieved by continuously determining the total amount of nitrogen oxide emissions generated over the monitoring period and comparing it to the limit value for nitrogen oxide emissions over that period. Referring to Figure 1, this means that the shaded areas above limit value 1 must never be larger than the shaded areas below limit value 1.

[0045] This allows the operation of a gas turbine plant to be made significantly more efficient, as ammonia consumption can be reduced, especially during phases with a high load level.

[0046] Although the invention has been further illustrated and described in detail by the preferred embodiment, 2024PF00177 11, the invention is not limited by the disclosed examples and other variations can be derived from them by the person skilled in the art without leaving the scope of protection of the invention.

[0047] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

Claims

2024PF00177 12 Patent claims 1. Computer-aided method for operating a gas turbine plant, wherein the gas turbine plant is operated phasewise at different load levels, wherein a limit value (1) for an average emission value of nitrogen oxide related to a recording period is set, characterized in that operating parameters are strategically planned over the calendar year such that, during operation at a low load level, the nitrogen oxide emissions (3) are deliberately kept below the limit value (1) for the average emission value in order to create an emission deficit, and during operation at a high load level, the nitrogen oxide emissions (3) are deliberately exceeded at least temporarily by utilizing the previously created emission deficit, thereby optimizing ammonia consumption over the entire calendar year.

2. The method according to claim 1, characterized in that the recording period is one calendar year and the emissions accounting is carried out continuously over the entire calendar year.

3. Method according to claim 1 or 2, characterized in that in a subsection, in particular in a first subsection, of the recording period the operating parameters are selected such that, regardless of the load level, the limit value (1) for the average emission value of nitrogen oxide is not exceeded.

4. Method according to one of the preceding claims, characterized in that the recording period is 30 minutes, one hour, three hours, six hours, twelve hours, 2024PF00177 13 24 hours, a week, a month or a year.

5. Method according to one of the preceding claims, characterized in that at least one further limit value (2) for the nitrogen oxide emissions (3) over a partial period of the recording period, whereby the operating parameters of the gas turbine plant are selected such that the nitrogen oxide emissions (3) do not exceed the respective further limit value (2) over the respective partial period.

6. Method according to claim 5, characterized in that the partial period has a duration of 30 minutes, one hour, three hours, six hours, twelve hours, 24 hours, one week or one month.

7. Method according to claim 5 or 6, characterized in that several further limit values ​​(2) for nitrogen oxide emissions are / will be set for different partial periods.

8. Method according to one of the preceding claims, characterized in that the respective recording period or the at least one sub-period are fixed periods or rolling periods.

9. Method according to one of the preceding claims, characterized in that the gas turbine system includes an SCR catalyst.

10. Method according to claim 9, characterized in that an auxiliary substance, in particular ammonia, is supplied to the SCR catalyst, wherein, preferably, an operating parameter for controlling the nitrogen oxide emissions (3) is the amount of auxiliary substance supplied. 2024PF00177 14 11. Gas turbine plant comprising means adapted to perform the method according to any of the preceding claims.

12. Gas turbine plant according to claim 11, characterized in that it contains an SCR catalyst, wherein the SCR catalyst in particular comprises means for supplying an auxiliary substance, preferably ammonia, wherein these comprise control means for controlling the amount of auxiliary substance.

13. Gas turbine plant according to claim 11 or 12, characterized in that it includes a control device for carrying out the method according to one of claims 1 to 10, and / or that the gas turbine plant includes measuring means for recording the nitrogen oxide emissions (3).

14. Computer program product comprising commands that cause the gas turbine plant according to one of claims 11 to 13 to execute the method according to one of claims 1 to 10.

15. Computer-readable medium on which the computer program product according to claim 14 is stored.

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