Disclosed is an ethylene and/or propylene cracker unit that uses recycled carbon dioxide as a working fluid. A boiler may also use recycled carbon dioxide as a working fluid. In either instance, instead of releasing high-purity CO.sub.2 into the atmosphere, the bulk of the CO.sub.2 is utilized as the working fluid and the produced CO.sub.2 is captured and sent to the pipeline for utilization or storage. These systems will minimize heat loss and achieve essentially zero CO.sub.2 emission to the air.

A system optionally including a carbon oxide reactor. A method for carbon oxide reactor control, optionally including selecting carbon oxide reactor aspects based on a desired output composition, running a carbon oxide reactor under controlled process conditions to produce a desired output composition, and/or altering the process conditions to alter the output composition.

A system optionally including a carbon oxide reactor. A method for carbon oxide reactor control, optionally including selecting carbon oxide reactor aspects based on a desired output composition, running a carbon oxide reactor under controlled process conditions to produce a desired output composition, and/or altering the process conditions to alter the output composition.

A chemical synthesis plant comprising: one or more reactors configured for producing, from one or more reactants, a process stream comprising at least one chemical product; a feed preparation system configured to prepare one or more feed streams comprising one or more of the one or more reactants for introduction into the one or more reactors; and/or a product purification system configured to separate the at least one chemical product from reaction byproducts, unreacted reactants, or a combination thereof within the process stream, wherein the chemical synthesis plant is configured such that a majority of the net energy needed for heating, cooling, compressing, or a combination thereof utilized via the one or more reactors, the feed preparation system, the product purification system, or a combination thereof is provided from a noncarbon based energy source, from a renewable energy source, and/or from electricity.

An olefin synthesis plant comprising: a feed pretreatment section configured to pretreat a feed stream; a pyrolysis section comprising one or more pyrolysis reactors configured to crack hydrocarbons in the feed stream in the presence of a diluent to produce a cracked gas stream; a primary fractionation and compression section configured to provide heat recovery from and quenching of the cracked gas stream; remove a component from the cracked gas stream; and compress the cracked gas stream, thus providing a compressed cracked gas stream; and/or a product separation section configured to separate a product olefin stream from the compressed cracked gas stream, wherein the olefin synthesis plant is configured such that, relative to a conventional olefin synthesis plant, more of the energy and/or the net energy required by the olefin synthesis plant and/or one or more sections thereof, is provided by a non-carbon based and/or renewable energy source and/or electricity.

A chemical synthesis plant comprising: one or more reactors configured for producing, from one or more reactants, a process stream comprising at least one chemical product; a feed preparation system configured to prepare one or more feed streams comprising one or more of the one or more reactants for introduction into the reactor; and/or a product purification system configured to separate the at least one chemical product from reaction byproducts, unreacted reactants, or a combination thereof within the process stream, wherein the chemical synthesis plant is configured such that a majority (e.g., greater than 50, 60, 70, 80, 90, or 100%) of the net energy needed for heating, cooling, compressing, or a combination thereof utilized via the one or more reactors, the feed preparation system, the product purification system, or a combination thereof is provided from an intermittent energy source (IES).

A chemical synthesis plant comprising: one or more reactors configured for producing, from one or more reactants, a process stream comprising at least one chemical product; a feed preparation system configured to prepare one or more feed streams comprising one or more of the one or more reactants for introduction into the reactor; and/or a product purification system configured to separate the at least one chemical product from reaction byproducts, unreacted reactants, or a combination thereof within the process stream, wherein the chemical synthesis plant is configured such that a majority (e.g., greater than 50, 60, 70, 80, 90, or 100%) of the net energy needed for heating, cooling, compressing, or a combination thereof utilized via the one or more reactors, the feed preparation system, the product purification system, or a combination thereof is provided from an intermittent energy source (IES).

An ammonia synthesis plant comprising: a feed pretreating section operable to pretreat a feed stream; a syngas generation section operable to reform the feed stream to produce a reformer product stream; a shift conversion section operable to subject the reformer product stream to the water gas shift reaction, to produce a shifted gas stream comprising more hydrogen than the reformer gas stream; a purification section operable to remove at least one component from the shifted gas stream, and provide an ammonia synthesis feed stream; and/or an ammonia synthesis section operable to produce ammonia from the ammonia synthesis feed stream, wherein the ammonia synthesis plant is configured such that, relative to a conventional ammonia synthesis plant, more of the energy required by the ammonia synthesis plant or one or more sections thereof is provided by a non-carbon based energy source, a renewable energy source, and/or electricity.

A method for preparing ethylene, including: passing a feed stream containing C1 and C2 hydrocarbon compounds through a first heat exchanger and feeding the feed stream passed through the first heat exchanger to a second gas-liquid separator; feeding a part of a bottom discharge stream of the second gas-liquid separator to a demethanizer, passing an overhead discharge stream of the second gas-liquid separator through a second heat exchanger, feeding the overhead discharge stream of the second gas-liquid separator passed through the second heat exchanger to a third gas-liquid separator; feeding a bottom discharge stream of the third gas-liquid separator to the demethanizer; feeding a bottom discharge stream of the demethanizer to a C2 separator; feeding an overhead discharge stream of the C2 separator to a second compressor; passing a part of a compressed discharge stream of the second compressor through the first heat exchanger and feeding the part of the compressed discharge stream of the second compressor passed through the first heat exchanger to the second compressor as a first circulation flow; passing a part of the compressed discharge stream of the second compressor through the second heat exchanger and feeding the part of the compressed discharge stream of the second compressor passed through the second heat exchanger to a first compressor as a second circulation flow; and feeding a compressed discharge stream of the first compressor to the second compressor, and an apparatus for preparing ethylene for implementing the same.

A method for preparing ethylene, including: passing a feed stream containing C1 and C2 hydrocarbon compounds through a first heat exchanger and feeding the feed stream passed through the first heat exchanger to a second gas-liquid separator; feeding a part of a bottom discharge stream of the second gas-liquid separator to a demethanizer, passing an overhead discharge stream of the second gas-liquid separator through a second heat exchanger, feeding the overhead discharge stream of the second gas-liquid separator passed through the second heat exchanger to a third gas-liquid separator; feeding a bottom discharge stream of the third gas-liquid separator to the demethanizer; feeding a bottom discharge stream of the demethanizer to a C2 separator; feeding an overhead discharge stream of the C2 separator to a second compressor; passing a part of a compressed discharge stream of the second compressor through the first heat exchanger and feeding the part of the compressed discharge stream of the second compressor passed through the first heat exchanger to the second compressor as a first circulation flow; passing a part of the compressed discharge stream of the second compressor through the second heat exchanger and feeding the part of the compressed discharge stream of the second compressor passed through the second heat exchanger to a first compressor as a second circulation flow; and feeding a compressed discharge stream of the first compressor to the second compressor, and an apparatus for preparing ethylene for implementing the same.