9 from the middle of the furnace to 3 cm downstream

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Unformatted text preview: d in the middle of the furnace. The temperature profile of the original furnace exhibited a strong temperature gradient (Fig. 9). From the middle of the furnace to 3 cm downstream, the temperature decreased by 162°C, from the middle to 1 cm downstream 35°C. Due to this large temperature gradient the furnace was regarded as not suitable for the purpose of the catalytic tests and therefore modified.  WHPSHUDWXUH >ƒ&@    UHEXLOG IXUQDFH  PRGLILHG IXUQDFH RULJLQDO IXUQDFH             GLVWDQFH IURP WKH PLGGOH RI WKH KHDWLQJ HOHPHQW >FP@ Fig. 9 Temperature profiles of the original, the modified and the rebuild furnace Since cold air circulating between the furnace and the reactor like in a chimney is suspected to be the main reason for the large temperature gradient, the top and bottom ends of the void between the furnace and the reactor were plugged with kaolinite wool (Fig. 8). This improved the temperature profile considerably. A short almost isothermal zone was found ca. 1 cm upstream the middle of the reactor. Nevertheless the furnace was still considered to be insufficient for various reasons. The temperature gradient in ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffyfffffffffffffffffffffffffffffffffffffffff 2. Experimental 71 ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffyfffffffffffffffffffffffffffffffffffffffff the 1cm long isothermal zone was still 5°C. Furthermore, the hottest zone in the reactor at which the catalyst bed must be placed was shifted upstream by about 1 cm. This means shortening of the time for the feed stream to heat up to the reaction temperature, which might be important when using high flow rates as demanded for the catalytic tests. A sufficient preheat of the feed stream had also to be questioned on the basis of the sloping shape of the temperature profile of the furnace (Fig. 9). A further problem is that it cannot be guarant...
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This document was uploaded on 10/07/2013.

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