16 with a radially outwardly projecting flange 17 at an upper end thereof the jacket 14 includes a lower dished end 18 which is welded to the wall 16 and a circular top 20 which is secured to the flange 17 by means of six circumferentially spaced m 22 bolts 22 fig1 shows the reactor 10 in an open condition with the top 20 spaced above the flange 17 however in use the reactor 10 is closed with the top 20 adjacent the flange 17 the jacket 14 being sealed each reactor coil 12 a 12 b 12 c 12 d has a surface to volume ratio of 2670 m u2212 1 the reactor coils 12 are immersed in a heat transfer fluid in this example oil contained within the jacket 14 the reactor coils 12 a 12 b 12 c 12 d were fabricated from u215b inch nominal size copper refrigeration tubing and were formed from straight lengths of the tubing which were bent into a coil shape and joined end to end to form the helical coils standard compression unions were used to join the individual lengths of tubing the jacket 14 was fabricated from a length of.