gases are then fed into a pressure equalizer 52 prior to entering second molecular sieve 24 the gas streams emerging from molecular sieve 24 are joined by gases from molecular sieve 18 and first and second heat recovery boilers 48 and 50 second retort 16 is indirectly heated using hot gases from second burner 22 the second burner 22 utilizes methane or natural gas plus cxhy from first molecular sieve 18 and is supplied with sufficient oxygen from second molecular sieve 24 to produce sub stoichiometic starved oxygen conditions to produce carbon monoxide co and hydrogen h 2 these hot gases are used to indirectly heat the retort then are sent to the second heat recovery boiler 50 which heats water to make steam the spent gases from this loop are then sent to second molecular sieve 24 where they are separated referring to fig2 and 3 the above process is shown in a flow diagram form an alternate process is shown in fig4 wherein only those portions that are different will be provide with different reference numbers and described herein in this embodiment the second molecular sieve is not used allowing co and h 2 into the first pressure vessel 28 without being metered the gases mostly co and h 2 from the.