Exxon Research and Engineering Company

Robert M Osman

Larry J Shulik

Robert G Byington

The present invention is generally directed to an improved process and apparatus for the production of gaseous products such as ammonia by catalytic, exothermic gaseous reactions and is specifically directed to an improved process which utilizes a gas-phase catalytic reaction of nitrogen and hydrogen for the synthesis of ammonia. This improved process for the production of ammonia utilizes an ammonia converter apparatus designed to comprise at least two catalyst stages and a reheat exchanger so arranged as to provide indirect heat exchange of the gaseous effluent from the last reactor catalyst stage with the effluent from at least one other reactor catalyst stage having a higher temperature level in order to reheat the effluent from the last reactor catalyst stage prior to exiting the reactor vessel, thereby facilitating higher level heat recovery from the reactor effluent.

Catalytic gas synthesis apparatus

In a process for producing ammonia which comprises: (a) primary catalytically reforming at super atmospheric pressure in a direct-fired primary reforming zone, a hydrocarbon feedstock with steam to produce a gas containing carbon oxides, hydrogen and methane; (b) secondary catalytically reforming the gas from step (a) by introducing air and bringing the mixture towards equilibrium thereby producing a secondary reformer effluent gas containing nitrogen, carbon oxides, hydrogen and a decreased quantity of methane; (c) converting carbon monoxide catalytically with steam to carbon dioxide and hydrogen; (d) removing carbon oxides to give an ammonia synthesis gas comprising nitrogen and hydrogen and compressing the gas to ammonia synthesis pressure; (e) reacting the synthesis gas in an ammonia synthesis zone to produce ammonia and recovering ammonia from the reacted gas to produce an ammonia-depleted gas stream; (f) recycling at least a portion of the ammonia-depleted gas stream to the ammonia synthesis zone; and (g) treating a sidestream of the ammonia-depleted gas to separate a stream enriched in hydrogen and an inerts-enriched gas stream, and returning the enriched hydrogen stream to the ammonia synthesis zone; the improvement which comprises: (i) operating step (b) at a temperature in the outlet gas of not greater than about 1735.degree. F. and with an amount of air sufficient to provide from about 3 to 11 molar % excess N.sub.2 and to form a secondary reformer outlet gas containing at least 0.8 vol. % methane; (ii) operating step (e) under conditions sufficient to provide at least 10 vol. % inert gases in the ammonia-depleted gas stream; and (iii) introducing as synthesis gas feed to the ammonia synthesis zone a mixture comprising the synthesis gas formed in step (d) having a methane content of at least about 1.2 mol. % CH.sub.4, on a dry basis, the recycled gas produced in step (f) plus the hydrogen-enriched gas stream formed in step (g), whereby the H.sub.2 loss from the process with the separated inerts enriched gas stream is minimized.

Low severity hydrocarbon steam reforming process

In a process for steam reforming of a hydrocarbon gas feedstream wherein: (a) the hydrocarbon gas feedstream is partially reformed at elevated temperatures in indirect heat exchange with hot combustion gases in a direct fired primary reforming furnace provided with a convection section for recovery of excess heat from said combustion gases; and (b) the partially reformed feedstream is then further reformed in the presence of an oxygen-containing gas and steam in a secondary reformer to form a secondary reformer gaseous effluent; the improvement which comprises recovering waste heat from said secondary reformer effluent gas and from said primary reforming combustion products by (i) heating a high pressure saturated steam in a first steam superheating zone by indirect heat exchange with at least a portion of said secondary reformer effluent gas to form a first superheated steam stream; and (ii) further heating said first superheated steam in a second steam superheating zone by indirect heat exchange with at least a portion of said primary reformer hot combustion gases to form a second superheated steam stream.

Hydrocarbon steam reforming using series steam superheaters

Catalytic gas synthesis process

A process for removing acid gases such as CO.sub.2 and H.sub.2 S from gas streams using a cyclic aqueous alkaline scrubbing solution which is circulated between an absorption and regeneration stage is disclosed. This process is improved by integrating within this cyclic system a process scheme wherein condensed steam having gaseous impurities dissolved therein is recovered from the feed gas and subjected to a pressure below which scrubbing solution regeneration takes place. While maintaining this pressure, the process condensate is heated, boiled and stripped to evolve a vaporous mixture comprising steam and gaseous impurities which are compressed and introduced into the regeneration stage. By this process, useful work is performed by low temperature process streams thereby improving the overall efficiency of the cyclic process.

Growing community of inventors

Parsippany, NJ, United States of America

Robert M Osman