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The development of a test rig to determine fouling factors of feedwater heaters
Feed water heaters are large shell and tube heat exchangers. They from part of the Rankine cycle used in coal fired power plants with the main purpose being the improvement of the overall cycle efficiency. Like most heat exchangers, feed water heaters suffer from fouling. Fouling is defined as “any...
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| Format: | Thesis |
| Language: | English |
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Department of Mechanical Engineering
2020
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| _version_ | 1867613540721885184 |
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| access_status_str | Open Access |
| author | Hallatt, Nicolaas |
| author2 | Fuls, Wim |
| author_browse | Fuls, Wim Hallatt, Nicolaas |
| author_facet | Fuls, Wim Hallatt, Nicolaas |
| author_sort | Hallatt, Nicolaas |
| collection | Thesis |
| description | Feed water heaters are large shell and tube heat exchangers. They from part of the Rankine cycle used in coal fired power plants with the main purpose being the improvement of the overall cycle efficiency. Like most heat exchangers, feed water heaters suffer from fouling. Fouling is defined as “any undesirable deposit on heat exchanger surfaces that increases resistance to heat transmission”. In the design of heat exchangers, fouling is accommodated by adding additional surface area to the heat exchanger. The amount of additional area is determined by the use of fouling factors. Although this is the only wide-spread method accepted in industry, the fouling factors in use are outdated, generally considered conservative and lead to oversized heat exchangers. The purpose of this study was to design and build a test rig that can accurately measure fouling factors of feed water heater tubes that has been in service for a full life cycle. A comprehensive literature study was performed to decide on the most effective test method, as well as the required instrument type and accuracy. The best method was found to be where the overall heat transfer coefficient for a fouled tube, outside cleaned tube (half clean) and clean tube was measured. The measured values are then converted to the internal, external and overall fouling factors. Validation test were done on the test rig. These included energy balance tests, theoretical comparison tests and repeatability tests. The results of all tests were acceptable and within measurement uncertainty limits. Five sample test tubes, obtained from a 30 year old LP heater at an Eskom power station, were tested. The results indicated that the average measured fouling factors were less than 20% of the commonly used HEI fouling factors. This is significantly lower and confirms that the fouling factors in use for this specific case are conservative. The test rig proved to be accurate and effective in measuring the fouling factors. Although the tests shows promising results, the small amount of tubes tested from only one heat exchanger are not sufficient to make meaningful conclusions. The test rig is now ready for a future study where a large sample of tubes can be tested. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/31774 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:37:46.759Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| 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:11427/31774 The development of a test rig to determine fouling factors of feedwater heaters Hallatt, Nicolaas Fuls, Wim Feedwater Heater Fouling Factors Test Rig Feed water heaters are large shell and tube heat exchangers. They from part of the Rankine cycle used in coal fired power plants with the main purpose being the improvement of the overall cycle efficiency. Like most heat exchangers, feed water heaters suffer from fouling. Fouling is defined as “any undesirable deposit on heat exchanger surfaces that increases resistance to heat transmission”. In the design of heat exchangers, fouling is accommodated by adding additional surface area to the heat exchanger. The amount of additional area is determined by the use of fouling factors. Although this is the only wide-spread method accepted in industry, the fouling factors in use are outdated, generally considered conservative and lead to oversized heat exchangers. The purpose of this study was to design and build a test rig that can accurately measure fouling factors of feed water heater tubes that has been in service for a full life cycle. A comprehensive literature study was performed to decide on the most effective test method, as well as the required instrument type and accuracy. The best method was found to be where the overall heat transfer coefficient for a fouled tube, outside cleaned tube (half clean) and clean tube was measured. The measured values are then converted to the internal, external and overall fouling factors. Validation test were done on the test rig. These included energy balance tests, theoretical comparison tests and repeatability tests. The results of all tests were acceptable and within measurement uncertainty limits. Five sample test tubes, obtained from a 30 year old LP heater at an Eskom power station, were tested. The results indicated that the average measured fouling factors were less than 20% of the commonly used HEI fouling factors. This is significantly lower and confirms that the fouling factors in use for this specific case are conservative. The test rig proved to be accurate and effective in measuring the fouling factors. Although the tests shows promising results, the small amount of tubes tested from only one heat exchanger are not sufficient to make meaningful conclusions. The test rig is now ready for a future study where a large sample of tubes can be tested. 2020-05-05T11:09:30Z 2020-05-05T11:09:30Z 2019 2020-05-04T08:26:51Z Master Thesis Masters MSc https://hdl.handle.net/11427/31774 eng application/pdf Department of Mechanical Engineering Faculty of Engineering and the Built Environment |
| spellingShingle | Feedwater Heater Fouling Factors Test Rig Hallatt, Nicolaas The development of a test rig to determine fouling factors of feedwater heaters |
| thesis_degree_str | Master's |
| title | The development of a test rig to determine fouling factors of feedwater heaters |
| title_full | The development of a test rig to determine fouling factors of feedwater heaters |
| title_fullStr | The development of a test rig to determine fouling factors of feedwater heaters |
| title_full_unstemmed | The development of a test rig to determine fouling factors of feedwater heaters |
| title_short | The development of a test rig to determine fouling factors of feedwater heaters |
| title_sort | development of a test rig to determine fouling factors of feedwater heaters |
| topic | Feedwater Heater Fouling Factors Test Rig |
| url | https://hdl.handle.net/11427/31774 |
| work_keys_str_mv | AT hallattnicolaas thedevelopmentofatestrigtodeterminefoulingfactorsoffeedwaterheaters AT hallattnicolaas developmentofatestrigtodeterminefoulingfactorsoffeedwaterheaters |