Abstract: A method for reacting one or more hydrocarbons by steam cracking including conducting one or more input streams containing the one or more hydrocarbons, obtaining one or more product streams, through one or more radiation zones of one or more cracker furnaces, in which the one or more radiation zones are heated by firing heating gas with combustion air, in which at least a portion of the combustion air is subjected to combustion air preheating in which steam is produced from feed water, and in which the feed water is subjected to feed water preheating in one or more convection zones of the one or more cracker furnaces. The combustion air preheating is carried out at least in part and/or at least temporarily using heat withdrawn from at least part of the feed water upstream of the feed water preheating.

Abstract: The invention relates to a burner (B) for firing a combustion chamber, having a supply duct (Z1) for supplying combustion gas or combustion air into the combustion chamber, wherein the burner (B) has an inlet opening (E) via which flue gas (4) can flow into the supply duct (Z1). To be able to adjust the flow rate of the flue gas (4) flowing into the supply duct (Z1), the burner (B) comprises an adjustable throttle device (D).

Abstract: Catalysts comprisingA) a rare earth alkoxide, a rare earth carboxylate and/or a rare earth coordination compound with diketones,B) an alumoxane andC) an inert, particulate, inorganic solid with a specific surface area of greater than 10 m.sup.2 /g and a pore volume of 0.3 to 15 ml/gare excellently suited to the polymerisation of conjugated dienes, in particular butadiene, in the gas phase.