| 摘要 |
PURPOSE:To cool a hot rolled steel plate in a stabilized state and to prevent the nonuniformity in temperature and cooling speed from occurring by injecting water on both upper and lower surfaces of the steel plate at a high temperature area where the cooling water injected on the hot rolled steel plate performs film boiling and by injecting water on the lower surface at a transition boiling area moving to the nuclear boiling. CONSTITUTION:When cooling water is sprayed on both upper and lower surfaces of the hot rolled steel plate, a vapor film is formed between the steel plate and a water film, a film boiling phenomenon is generated and the reduction of temperature of the hot rolled steel plate becomes small for the amount of water. The cooling water sprayed on the hot rolled steel plate of a comparatively low temperature forms a water film, part of the water film makes bubbles to generate the nuclear boiling phenomenon and the temperature of the hot rolled steel plate is lowered suddenly. At this transition boiling area, the injection of the cooling water from the upper side water injection header is stopped and the cooling water is sprayed from the lower side water injection header only. The cooling water sprayed from the lower side does not form vapor film on the boundary surface of the hot rolled steel plate and cools the hot rolled steel plate at the rate responding to the amount of water. |
