GB671658A - Apparatus for heating fluids - Google Patents

Abstract

This Specification relates to apparatus for carrying out the process for making low-boiling unsaturated hydrocarbons which is the subject of Specification 671,635. The apparatus is described in the Group III abridgment of the present Specification. Specification 498,477, [Group III], also is referred to.ALSO:<PICT:0671658/III/1> <PICT:0671658/III/2> A tubular furnace for heating fluids comprises vertical side walls 1 and end walls (not shown) defining a radiant heating zone which is divided by a wall 7 into two separate zones containing respectively banks 19 and 20 of vertical tubes, sloping walls 2 defining with the end walls an intermediate radiant and convection heating zone and containing two banks of horizontal tubes 17 and 18 respectively adjacent the two sloping walls, upper walls 3 defining with the end walls an upper convection heating section of lesser width than the lower portion of the chamber and containing a plurality of horizontal tubes 16, burners for directing combustible mixture of fuel and air upwardly against the opposite faces of the wall 7, and a flue 15 above the upper convection section for withdrawing hot gases from the furnace. In the furnace shown a row of oil burners 11 and gas burners 14 are provided. In Fig. 2 the tubes in two of the furnaces shown in Fig. 1 are interconnected to provide an arrangement for converting normally liquid paraffinic hydrocarbons to lower boiling unsaturated hydrocarbons. In an example a paraffinic gas oil is heated to 260 DEG C. in tubes 26 and 261, steam is heated to 1060 DEG C. in tubes 28 and 281 and the two streams mixed with a resultant temperature of 370 DEG C. and fed to tubes 32 and 321. In tubes 32 and 321 the mixture is heated, with a minimum of cracking, up to 700 DEG C. and is discharged and fed at 2 atmospheres pressure to tubes 35 and 351 where it is heated to 700 DEG C. for 1.5 seconds. The output from tubes 35 and 351 consisting mainly of a mixture of ethylene, propylene, butylene, butadiene and acetylene and comprising also paraffinic gases and hydrogen is cooled by a quench oil stream in chamber 39. In another example a paraffinic stream is heated to 760 DEG C. with steam in tubes 32 and 321 and is then subjected to low pressure conversion in tubes 35 and 351 at 760 DEG C. for 1.5 seconds. The tubes 16, Fig. 1, may serve to preheat the paraffinic hydrocarbon charge or the steam. Specifications 498,477 and 671,635 are referred to.