believed sufficient to provide optimum gas distribution so internal piping was provided in the second reaction zone to split the incoming gas flow into two streams and the discharge points of these streams were placed 180 u00b0 apart from one another each of these discharge points in turn split the flow into two directions so that gas entering and leaving the second reactor section did so via four symmetrically spaced openings on both the inlet and outlet to zone 2 to provide maximum heater efficiency the screen separating zone 1 from zone 2 was baffled over two meters of its length or a little more than three times the thickness of the catalyst bed this will insure that over 90 of the gas leaving zone 1 will do so via the interheater the screen baffle defining the upper and lower portions within zone 2 was only 1 2 meters thick or twice the thickness of the catalyst bed this meant that gas would have about as easy a path to take in flowing laterally across the catalyst bed as down through the catalyst bed in the section around this baffle point this is not harmful as it does not matter if the reactants contact catalyst in radial or downflow as long as contact occurs the baffle separating zone 2 from zone 3 was two.