ATR-based hydrogen process and plant
A plant and process for producing a hydrogen rich gas are provided, said process comprising the steps of: reforming a hydrocarbon feed in a reforming step using an autothermal reformer (ATR) thereby obtaining a synthesis gas comprising CH 4 , CO, CO 2 , H 2 and H 2 O; shifting said synthesis gas in a shift configuration including a high temperature shift step; passing the shifted syngas to a first hydrogen purification unit, e.g. a PSA unit; passing a portion of the off-gas from the first hydrogen purification unit to a second hydrogen purification unit, and using off-gas from the first and second hydrogen purification unit as e.g. fuel for a preheater unit before the ATR.
1 . A plant for producing a H 2 -rich stream from a main hydrocarbon feed, said plant comprising:
a reforming section, said reforming section comprising an autothermal reformer (ATR), said ATR being arranged to receive a hydrocarbon feed and convert it to a stream of syngas;
a shift section, said shift section comprising a high temperature shift (HTS) unit, said high temperature shift unit being arranged to receive a stream of syngas from the ATR and shift it in a high temperature shift step, thereby providing a shifted syngas stream;
a water separation section, said water separation section comprising a separator unit, said water separation section arranged to receive the shifted syngas stream from said shift section and separating water from said shifted syngas stream as a process condensate stream in said separator unit, thereby providing a water-depleted shifted syngas stream;
a first hydrogen purification unit, arranged to receive said water-depleted shifted syngas stream from said separator unit, and separate it into a first high-purity H 2 stream and a first off-gas stream;
means for separating said first off-gas stream into a first off-gas fuel stream and a first off-gas feed stream;
a second hydrogen purification unit, arranged to receive said first off-gas feed stream and separate it into a second high-purity H 2 stream and a second off-gas fuel stream; and
said reforming section further comprises at least one fired heater arranged to pre-heat said main hydrocarbon feed prior to it being fed to said ATR, and said plant is arranged to feed said first off-gas fuel stream and/or said second off-gas fuel stream as fuel for said at least one fired heater,
wherein said plant further comprises a compressor arranged for compressing said first off-gas feed stream prior to it being fed to said second hydrogen purification unit,
wherein said reforming section further comprises at least one pre-reforming unit which is arranged upstream the ATR to pre-reform said main hydrocarbon feed and form said hydrocarbon feed prior to it being fed to the ATR,
wherein said reforming section further comprises a hydrogenator unit, a sulfur absorption unit arranged upstream said at least one pre-reformer unit, and a hydrogen-recycling compressor for feeding a portion of said first high-purity H 2 stream into said main hydrocarbon feed prior to it being fed to the feed side of said at least one pre-reformer unit or prior to it being fed to the feed side of said hydrogenator,
wherein said plant is without a CO2-removal section downstream said shift section and upstream said water separation section.
2 . The plant according to claim 1 , wherein said plant is without a steam methane reformer unit (SMR) upstream the ATR.
3 . The plant according to claim 1 , wherein the first high-purity H 2 stream is mixed with the second high-purity H 2 stream to form a hydrogen-rich stream.
4 . The plant according to claim 2 , wherein said first off-gas fuel stream and/or said second off-gas fuel stream are mixed to form a combined off-gas fuel stream prior to being fed as fuel for said at least one fired heater.
5 . The plant according to claim 1 , wherein said first hydrogen purification unit and said second hydrogen purification unit are selected from a pressure swing adsorption (PSA) unit, a hydrogen membrane, a cryogenic separation unit, or combinations thereof.
6 . The plant according to claim 1 , wherein the high temperature shift (HTS) unit comprises a promoted zinc-aluminium oxide based high temperature shift (HTS) catalyst.
7 . The plant according to claim 1 , wherein the shift section comprises one or more additional high temperature shift units in series, and/or one or more additional shift units downstream the high temperature shift unit.
8 . The plant according to claim 1 , wherein the shift section is the only shift section on the stream of syngas.
9 . The plant according to claim 1 , wherein there is no shift section on any of:
the first off-gas stream, the first off-gas fuel stream, the first off-gas feed stream and the second off-gas fuel stream.
10 . A process for producing a H 2 -rich stream from a main hydrocarbon feed, said process comprising the steps of:
providing a plant according to claim 1 ;
supplying a hydrocarbon feed to the ATR and converting it to a stream of syngas;
supplying a stream of syngas from the ATR to the shift section, and shifting it in a high temperature shift step, thereby providing a shifted gas stream;
supplying the shifted gas stream from the shift section to a water separation section, and separating water from said shifted syngas stream as a process condensate stream in a separator unit, thereby providing a water-depleted shifted syngas stream;
supplying said water-depleted syngas stream to a first hydrogen purification unit, and separating it into a first high-purity H 2 stream and a first off-gas stream,
separating said first off-gas stream into a first off-gas fuel stream and a first off-gas feed stream;
feeding said first off-gas feed stream into a second hydrogen purification unit and separating it into a second high-purity H2 stream and a second off-gas fuel stream; and
pre-heating said main hydrocarbon feed prior to being fed to said ATR in at least one fired heater, and feeding said first off-gas fuel stream and/or said second off-gas fuel stream as fuel for said at least one fired heater,
wherein the process further comprises pre-reforming said main hydrocarbon feed in at least one pre-reforming unit to form a hydrocarbon feed prior to it being fed to the ATR, and mixing a portion of said first high-purity H 2 stream with main hydrocarbon feed before being fed to the feed side of said at least one pre-reforming unit, and
wherein the process further comprises compressing said first off-gas feed stream prior to it being fed to said second hydrogen purification unit.
11 . The process according to claim 10 , wherein the steam to carbon ratio of the synthesis gas supplied from the ATR to the shift section is less than 2.0.
12 . The process according to claim 10 , wherein the steam to carbon ratio defined as the molar ratio of all steam added upstream the shift section to the carbon of main hydrocarbon feed and/or hydrocarbon feed, is 2.6-0.1.
13 . The process according to claim 10 , wherein the process further comprises adding steam to any of: main hydrocarbon feed, hydrocarbon feed, an oxygen stream fed to the ATR, ATR, HTS unit, additional shift units downstream the HTS unit, or combinations thereof.