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Show The currently adopted tube material configuration is shown in Table 2: SiC 47% and 30% for above the slag line, SiC 45% and C 35% for below the slag line, and SiC 46% and C 33%, intermediate between above and below, for around the slag line. This is primarily due to the characteristic of C, which has excellent thermal conductivity and thermal shock resistance, but is liable to oxidation. lli. Immersion and 8ath-type Holding Furnace Because it is difficult to produce a large capacity burner tube due to the severe durability requirements, the development of immersion-type heating system started at a holding furnace, which does not need a large capacity. 1. Specifications The bath-type holding furnace is available in capacities ranging from 300kg to 1,OOOkg. The specifications of 750kg type is shown in Table 1. Table 1 Specification of the Immersion and Bath-type Holding Furnace Model Capacity Dimensions Diameter of the furnace Total length Maximum input (kcallh) Power requirement (kwN) Heating up rate (OC/h) Heat consumption (kcallh) 2. Performance ASK750 750kg 1,480 1,700 3x104 0.5/200 40°C 11,300 *1 *2 * 1: while running or start up after holdings. *2: while running We tested one of the holding furnaces under the following conditions. The results are shown below. Conditions Holding capacity Temperature to be held at Aluminum material Holding time Results Unit heat consumption Outlet fully close Outlet open Heating up rate Surface temperature of furnace 750kg 700°C AC4C More than 72 hours 10.4 kcallkg-h 16.0 kcal/kg-h 33.3°C/h 40 to 53°C The effective output of the immersion tube burner is high at 70%, whereas the surface temperature of the furnace is low, the surface heat loss being 33%. 4 |