The king was so angry that rage is spoken of as if it were filling him up. Alternate translation: "Nebuchadnezzar became extremely angry" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Here "seven times hotter" is an idiom that means to make it very much hotter. This can be stated in active form. Alternate translation: "He commanded his men to make the furnace very much hotter than they normally make it" (See: [[rc://en/ta/man/translate/figs-idiom]] and [[rc://en/ta/man/translate/figs-activepassive]])