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.

The ammonia synthesis system of the present invention includes an ammonia synthesis reaction unit that synthesizes ammonia from nitrogen and hydrogen; an ammonia cooler that cools an ammonia-containing gas discharged from the ammonia synthesis reaction unit; a gas-liquid separator that separates ammonia liquefied by the ammonia cooler from a circulated gas; and an ammonia synthesizing gas supplying unit that supplies nitrogen gas and hydrogen gas, the circulated gas being supplied to the ammonia synthesis reaction unit, the circulated gas supplied to the ammonia synthesis unit having an ammonia gas concentration of 3% by volume or more. The method for producing ammonia of the present invention includes reacting nitrogen and hydrogen using a circulated gas having an ammonia gas concentration of 3% by volume or more and using an ammonia synthesis catalyst under a condition of a reaction pressure of 10 MPa or less to produce ammonia.

The ammonia synthesis system of the present invention includes an ammonia synthesis reaction unit (10) that synthesizes ammonia from nitrogen and hydrogen; an ammonia cooler (20) that cools an ammonia-containing gas discharged from the ammonia synthesis reaction unit (10); a gas-liquid separator (30) that separates ammonia liquefied by the ammonia cooler (20) from a circulated gas; and an ammonia synthesizing gas supplying unit (40) that supplies nitrogen gas and hydrogen gas, the circulated gas being supplied to the ammonia synthesis reaction unit, the circulated gas supplied to the ammonia synthesis unit having an ammonia gas concentration of 3% by volume or more. The method for producing ammonia of the present invention includes reacting nitrogen and hydrogen using a circulated gas having an ammonia gas concentration of 3% by volume or more and using an ammonia synthesis catalyst under a condition of a reaction pressure of 10 MPa or less to produce ammonia. The present invention can provide an ammonia synthesis system and an ammonia production method in which an energy required for producing ammonia is reduced.

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

A process for synthesis of ammonia including generation of makeup gas in a frontend and conversion of said makeup gas in an ammonia synthesis loop including a circulator, a converter, a condensation section and a liquid ammonia separation section, including: when the loop operates at a partial load and a flow rate of makeup gas transferred from the front end to the synthesis loop is reduced, the loop is controlled by separating a gas stream from a converter feed line at a point upstream of the converter thus forming a bypass stream, reintroducing said bypass stream at the suction side of the circulator or at a point of the loop downstream of said separation section.

A method for controlling a synthesis loop for production of a chemical product, such as ammonia or methanol, wherein a feed rate of the loop depends on at least one source of renewable energy, the pressure of the loop and the delivery rate of a makeup compressor and of a circulation compressor are continuously controlled to follow the variable rate of the feed while maintaining the loop pressure within a target deviation from a design loop pressure.

An ammonia synthesis system, an operation method thereof, and an ammonia synthesis method are provided. The system includes a compressor for compressing mixed gas; a feed supply line for supplying the mixed gas to the compressor; an ammonia synthesis reactor for synthesizing ammonia by feeding the mixed gas compressed by the compressor into the reactor; an air separation unit for separating nitrogen from air; a first cooler for cooling syngas including ammonia discharged from the ammonia synthesis reactor; and a second cooler for heat-exchanging gaseous nitrogen separated by the air separation unit with the syngas cooled by the first cooler, wherein gaseous nitrogen heat-exchanged by the second cooler is supplied to the feed supply line.

An ammonia synthesis system includes an ammonia synthesis reaction unit that synthesizes ammonia from nitrogen and hydrogen; an ammonia cooler that cools an ammonia-containing gas discharged from the ammonia synthesis reaction unit; a gas-liquid separator that separates ammonia liquefied by the ammonia cooler from a circulated gas; and an ammonia synthesizing gas supplying unit that supplies nitrogen gas and hydrogen gas. The circulated gas supplied to the ammonia synthesis unit has an ammonia gas concentration of 3% by volume or more. A method for producing ammonia includes reacting nitrogen and hydrogen using a circulated gas having an ammonia gas concentration of 6% by volume or more and using an ammonia synthesis catalyst under a condition of a reaction pressure of 10 MPa or less to produce ammonia. The ammonia synthesis system and ammonia production method have a reduced energy requirement.