| OCR Text |
Show 8 experienced various revamping construction work since 1988. As for the slab reheating process, it used to have 4 slab reheating furnaces (No.1~No.4 furnace). At the early stage of revamping works, No.4 furnace was renewed in 1990. After that, No. 5 f u rnace was const ructed i n 1993 at the same ti me as the ol d No. 3 f u rnace was shut down. Each of the new furnaces, No.4 and No.5, has a walking beam type slab conveyance device, and was equipped with a recuperator that made it possible to obtain preheated air at the temperature of 920K. Although they had sufficient heating capacity individually, they were not able to demonstrate their full-capacity when they were used in combination with old furnaces, No.1 and No.2. Due to the pusher-type slab conveyance devices of the old furnaces, defects on the bottom surface of the reheated slab have often troubled us. In order to solve such problems, No.3 furnace was newly constructed in 1996 i nstead of the ol d furnaces as shown i n Fi g. 7. The newl y devel oped HRS was ful 1 y applied to the new furnace. This was the first time it had been applied to such a large reheating furnace. 4-2. Specification of new furnace Table 1 shows the major hardware specifications of the new furnace, and Fig.8 shows the schematic diagram of the furnace. 4-3. Effect of furnace revamping Fig.9 shows the change in the monthly production rate of No.1 hot strip mill of Fukuyama. It was improved after of No.3 furnace began operating in December, 1996. Fig. 10 shows the comparison of the fuel consumption. Energy saving by No.3 furnace is about 25% in comparison with the replaced old furnaces, and about 8% in comparison with No.4 and No.5 furnace. Total fuel consumption of No.1 hot strip mill reduced by about 13% after the revamping. Fig. 11 shows the periodical change of temperature of furnace gas, preheated air and exhaust gas in a burner. The temperature of preheated air is almost |
