Publication detail

OVERCOOLING IN OVERLAPPING AREAS DURING HYDRAULIC DESCALING

POHANKA, M. VOTAVOVÁ, H.

Original Title

OVERCOOLING IN OVERLAPPING AREAS DURING HYDRAULIC DESCALING

English Title

OVERCOOLING IN OVERLAPPING AREAS DURING HYDRAULIC DESCALING

Type

conference paper

Language

en

Original Abstract

The production and processing of high quality grades of steel is connected with oxidation at high temperatures. Unwanted scales are formed on the steel surface, which is usually heated over 900°C. These scales are often removed by hydraulic descaling during production. In most cases where long, flat products are produced, one row of descaling nozzles is used. Because these flat jet nozzles are arranged in the row, the water spray from one nozzle interferes with the spray from neighboring nozzles. This zone is called an overlap area and oftentimes more scales remain here after the descaling process. An increased amount of scales left behind result in a lower quality final product. The typical configuration with an inclination and twist angle equal to 15° was studied. Heat transfer coefficients (HTC) and surface temperatures were measured in the overlap area and compared with values obtained from undisturbed areas. It was found that the overlap area is grossly overcooled. Results were compared with a new configuration, where the twist angle was changed to 0°, and it was found that the overcooling was significantly reduced. Temperature measurement showed that the increased thickness of the scales in the overlap area can also be caused by surface overcooling because the scales change material properties with temperatures, and are therefore more difficult to remove. The new configuration with a twist angle of 0° seems to promise to improve the quality of hydraulic descaling.

English abstract

The production and processing of high quality grades of steel is connected with oxidation at high temperatures. Unwanted scales are formed on the steel surface, which is usually heated over 900°C. These scales are often removed by hydraulic descaling during production. In most cases where long, flat products are produced, one row of descaling nozzles is used. Because these flat jet nozzles are arranged in the row, the water spray from one nozzle interferes with the spray from neighboring nozzles. This zone is called an overlap area and oftentimes more scales remain here after the descaling process. An increased amount of scales left behind result in a lower quality final product. The typical configuration with an inclination and twist angle equal to 15° was studied. Heat transfer coefficients (HTC) and surface temperatures were measured in the overlap area and compared with values obtained from undisturbed areas. It was found that the overlap area is grossly overcooled. Results were compared with a new configuration, where the twist angle was changed to 0°, and it was found that the overcooling was significantly reduced. Temperature measurement showed that the increased thickness of the scales in the overlap area can also be caused by surface overcooling because the scales change material properties with temperatures, and are therefore more difficult to remove. The new configuration with a twist angle of 0° seems to promise to improve the quality of hydraulic descaling.

Keywords

scales, steel, water, hydraulic, descaling, overlapping, temperature, heat transfer coefficient, surface

RIV year

2015

Released

28.09.2015

Publisher

Inštitut za kovinske materiale in tehnologije, Ljubljana, Lepi pot 11,

Location

Ljubljana

ISBN

978-961-92518-8-1

Book

Book of abstracts

Edition

23rd International Conference on Materials and Technology

Edition number

23

Pages from

199

Pages to

199

Pages count

1

Documents

BibTex


@inproceedings{BUT117646,
  author="Michal {Pohanka} and Helena {Votavová}",
  title="OVERCOOLING IN OVERLAPPING AREAS DURING HYDRAULIC DESCALING",
  annote="The production and processing of high quality grades of steel is connected with oxidation at high temperatures. Unwanted scales are formed on the steel surface, which is usually heated over 900°C. These scales are often removed by hydraulic descaling during production. In most cases where long, flat products are produced, one row of descaling nozzles is used. Because these flat jet nozzles are arranged in the row, the water spray from one nozzle interferes with the spray from neighboring nozzles. This zone is called an overlap area and oftentimes more scales remain here after the descaling process. An increased amount of scales left behind result in a lower quality final product. The typical configuration with an inclination and twist angle equal to 15° was studied. Heat transfer coefficients (HTC) and surface temperatures were measured in the overlap area and compared with values obtained from undisturbed areas. It was found that the overlap area is grossly overcooled. Results were compared with a new configuration, where the twist angle was changed to 0°, and it was found that the overcooling was significantly reduced. Temperature measurement showed that the increased thickness of the scales in the overlap area can also be caused by surface overcooling because the scales change material properties with temperatures, and are therefore more difficult to remove. The new configuration with a twist angle of 0° seems to promise to improve the quality of hydraulic descaling.",
  address="Inštitut za kovinske materiale in tehnologije, Ljubljana, Lepi pot 11,",
  booktitle="Book of abstracts",
  chapter="117646",
  edition="23rd International Conference on Materials and Technology",
  howpublished="electronic, physical medium",
  institution="Inštitut za kovinske materiale in tehnologije, Ljubljana, Lepi pot 11,",
  year="2015",
  month="september",
  pages="199--199",
  publisher="Inštitut za kovinske materiale in tehnologije, Ljubljana, Lepi pot 11,",
  type="conference paper"
}