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Boiler feed pump low load – leak off recirculation study
For power plants that make use of high energy boiler feed pumps, there is a risk that the boiler feed pump may experience cavitation and overheating at low load and start-up conditions. These plants make use of a leak off or recirculation system that diverts some of the flow back to the feed water t...
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| Format: | Thesis |
| Language: | English |
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Department of Mechanical Engineering
2021
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| _version_ | 1867613164420464640 |
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| access_status_str | Open Access |
| author | van Tonder, Daniël |
| author2 | Fuls, Wim |
| author_browse | Fuls, Wim van Tonder, Daniël |
| author_facet | Fuls, Wim van Tonder, Daniël |
| author_sort | van Tonder, Daniël |
| collection | Thesis |
| description | For power plants that make use of high energy boiler feed pumps, there is a risk that the boiler feed pump may experience cavitation and overheating at low load and start-up conditions. These plants make use of a leak off or recirculation system that diverts some of the flow back to the feed water tank, ensuring that a minimum flow through the pump is maintained at low load and start-up operating conditions. The recirculation valve, also known as a leak off valve, experiences a very high pressure difference and cavitation pitting is common due to the water being close to saturation. There are various ways in which the recirculation flow is controlled in the industry such as open orifice, on/off binary type control valves, automatic recirculation valves (ARC) or modern modulating leak off systems. The valves themselves can also be simple plug type or make use of pressure staging to reduce the risk of cavitation. This project involves modelling the flow system around the boiler feed pump and its control for the various architectures employed in Eskom. This is to assist in understanding the reasons for cavitation damage that is found in some recirculation valves as well as the low load capability of the system. Single stage components with extremely high pressure drops are singled out as components with the highest risk of cavitation in the systems. Although extremely high pressure drops are found across the leak off valves themselves, the majority of the valves are multistage valves which are specifically designed to accommodate cavitation development and are therefore not of major concern. Some of the findings of the study are: The rule of thumb used within Eskom to determine the amount of pressure reducing stages on leak off valves could be more conservative. The specification of new valves and components for the leak off systems requires accurate specification based on detailed process models, such as the ones developed for this study. The full range of all possible operational cases must also be considered during the design. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/35389 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:31:47.142Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | Department of Mechanical Engineering |
| publisherStr | Department of Mechanical Engineering |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/35389 Boiler feed pump low load – leak off recirculation study van Tonder, Daniël Fuls, Wim Boiler Feed Pump Leak Off Cavitation Pressure Drop Critical Valve For power plants that make use of high energy boiler feed pumps, there is a risk that the boiler feed pump may experience cavitation and overheating at low load and start-up conditions. These plants make use of a leak off or recirculation system that diverts some of the flow back to the feed water tank, ensuring that a minimum flow through the pump is maintained at low load and start-up operating conditions. The recirculation valve, also known as a leak off valve, experiences a very high pressure difference and cavitation pitting is common due to the water being close to saturation. There are various ways in which the recirculation flow is controlled in the industry such as open orifice, on/off binary type control valves, automatic recirculation valves (ARC) or modern modulating leak off systems. The valves themselves can also be simple plug type or make use of pressure staging to reduce the risk of cavitation. This project involves modelling the flow system around the boiler feed pump and its control for the various architectures employed in Eskom. This is to assist in understanding the reasons for cavitation damage that is found in some recirculation valves as well as the low load capability of the system. Single stage components with extremely high pressure drops are singled out as components with the highest risk of cavitation in the systems. Although extremely high pressure drops are found across the leak off valves themselves, the majority of the valves are multistage valves which are specifically designed to accommodate cavitation development and are therefore not of major concern. Some of the findings of the study are: The rule of thumb used within Eskom to determine the amount of pressure reducing stages on leak off valves could be more conservative. The specification of new valves and components for the leak off systems requires accurate specification based on detailed process models, such as the ones developed for this study. The full range of all possible operational cases must also be considered during the design. 2021-11-29T10:03:16Z 2021-11-29T10:03:16Z 2020 2021-11-26T09:43:52Z Master Thesis Masters MSc http://hdl.handle.net/11427/35389 eng application/pdf Department of Mechanical Engineering Faculty of Engineering and the Built Environment |
| spellingShingle | Boiler Feed Pump Leak Off Cavitation Pressure Drop Critical Valve van Tonder, Daniël Boiler feed pump low load – leak off recirculation study |
| thesis_degree_str | Master's |
| title | Boiler feed pump low load – leak off recirculation study |
| title_full | Boiler feed pump low load – leak off recirculation study |
| title_fullStr | Boiler feed pump low load – leak off recirculation study |
| title_full_unstemmed | Boiler feed pump low load – leak off recirculation study |
| title_short | Boiler feed pump low load – leak off recirculation study |
| title_sort | boiler feed pump low load leak off recirculation study |
| topic | Boiler Feed Pump Leak Off Cavitation Pressure Drop Critical Valve |
| url | http://hdl.handle.net/11427/35389 |
| work_keys_str_mv | AT vantonderdaniel boilerfeedpumplowloadleakoffrecirculationstudy |