In a process for operating an ammonia plant, a gas mixture comprising nitrogen, hydrogen and ammonia is conveyed cyclically in a synthesis circuit with a conveying device which comprises at least a first compressor, nitrogen and hydrogen are converted at least partly into ammonia in a converter, the gas mixture is cooled in a cooling device in such a way that ammonia condenses out of the gas mixture, and hydrogen is provided at least partly by electrolysis. In this process, the utilization of fluctuating renewable energies can be integrated into existing plant designs, for the provision of hydrogen; for this reason, a master controller is provided and the master controller keeps at least the pressure in the synthesis circuit approximately constant via at least one control loop, on the basis of the anticipated amount of hydrogen. For this, the apparatus comprises a first bypass line for circumventing the first compressor, and a second bypass line for circumventing the cooling device.

A production unit 100 includes a production apparatus 20 including: a reaction tube U in which a catalyst material Q containing noble metal is housed; a first supply path R1 configured to supply a source gas (exhaust gas) G1 containing NOx and oxygen to the reaction tube U; a second supply path R2 configured to supply a reducing gas G2 not containing NOx to the reaction tube U; and a recovery path R3 configured to recover produced ammonia from the reaction tube U, and a control apparatus 30 configured to control the production apparatus 20, wherein the control apparatus 30 makes the production apparatus 20 perform a production process including: a first step of supplying the source gas G1 to the catalyst material Q to store NOx in the source gas G1 in the catalyst material Q, and a second step of stopping supply of the source gas G1 and then supplying the reducing gas G2 to the catalyst material Q to produce and recover ammonia from NOx stored in the catalyst material Q.

Methods for producing renewable ammonia are disclosed. Systems for implementing the methods are also disclosed.

Isothermal catalytic reactor (1) comprising a catalytic bed (2) and a tubular heat exchanger immersed in said catalytic bed, wherein the exchanger is formed by straight tubes connected to a distributor (6) and to a header (7) formed by preferably toroidal bodies which support the said tubes, and wherein the catalytic bed is of the type crossed by an inward radial flow.

A process and system for the generation of synthesis gas that is provided, in particular, for preparing hydrocarbon-containing fuel, ammonia or urea. The process follows the steps of providing a first feed gas stream of methane and reacting the first feed gas stream with steam in a reforming step, obtaining a synthesis gas stream of CO and H.sub.2. It is further provided that at least one first substream is separated off from the feed gas stream before the reforming step, the first substream is then burnt with a second feed gas stream of at least 95% by volume oxygen to give an exhaust gas stream comprising CO.sub.2 and water, and at least one part of the exhaust gas stream is recirculated to the feed gas stream after the first substream is separated off.