Development of accelerated cooling for new plate mill

Abstract

The aim of the paper is to design the new wide plate mill. The work on the new cooling technology was supported by extensive laboratory testing while a simulator with full scale testing of cooling units was used. The principal objective of the investigation was to establish the design specification of equipment for accelerated cooling, particularly with respect to the product dimensions and steel grades. The possibilities of accelerated cooling are limited by technical parameters of cooling equipment such as thickness of water layer, flowrate, spray height, position of cooled surface to the nozzles and water or plate speed. These parameters were studied for different product temperatures and water impingement densities from 50 to 110 l s⁻¹ m⁻². The heat transfer coefficient was determined and compared for each case. There were three recognised significant cooling regions: water layer region, impinging jet region without water layer and impinging region with water layer, which must be taken into account. The application of the new cooling technology showed better flatness product and productivity higher than previous accelerated cooling system, even shorter cooling length. The rejection ratio by flatness problem of new mill was nearly half of the previous one.

Keywords:

• Accelerated cooling
• Plate mill
• New cooling technology
• Spray cooling
• Heat transfer coefficient
• Experimental

The development of evaluation methods used in the present research has been supported within the project no. CZ·1·07/2·3·00/20·0188, HEATEAM-Multidisciplinary Team for Research and Development of Heat Processes.