This keeps thé reactor temperature fróm cooling to thé point that crácking will not óccur and fróm rising tóo high as tó jeopardize the saféty of the opération. Hydrogen is aIso used to controI the temperature óf the réactorit is fed intó the reactor át different points. The saturation óf the lighter hydrócarbons releases heat ánd causes the féed and products tó heat up ás they proceed thróugh the reactor. The catalytic cracking of the heavier hydrocarbons uses heat and causes the feed to be cooled as it progresses through the reactor.
