A method for revamp of an existing ammonia or urea plant and decarbonizing an ammonia / urea plant

Abstract

A method for revamp and decarbonizing an ammonia or urea plant comprising an existing primary and secondary steam reforming unit for the preparation of ammonia synthesis gas and an ammonia synthesis loop using an electrolysis unit to produce hydrogen and oxygen.

Description

[0001] Title: A method for revamp of an existing ammonia or urea plant and decarbonizing an ammonia / urea plant

[0002] The method involves revamping an existing ammonia or urea plant by adding an electrolysis unit and an autothermal reformer. The electrolysis unit produces hydrogen and oxygen, while the autothermal reformer is installed parallel to the existing reforming unit. The oxygen produced in the electrolysis unit is supplied to the autothermal reformer, and the hydrogen is supplied to the synthesis gas compressor. The method also includes reducing fuel consumption in the primary reformer, thereby reducing carbon emissions. The electrolyzer used can be a Solid Oxide Electrolysis Cell (SOEC), Alkaline, or Proton Exchange Membrane (PEM).

[0003] The invention pertains to the development of hybrid ammonia technology. It involves the installation of a renewable-electricity-powered electrolyzer for the production of green hydrogen and oxygen. The green hydrogen is added to the suction of a synthesis gas compressor, while the oxygen is used for autothermal reforming in an ATR installed parallel to the existing reforming section.

[0004] Ammonia production is a critical process in various industries, including agriculture, where it is used to produce fertilizers. The conventional method of ammonia production involves the use of natural gas and steam in a process known as steam methane reforming. This process, while effective, results in significant carbon emissions, contributing to environmental pollution. Furthermore, the process is energy-intensive, requiring large amounts of heat to drive the reactions. This has led to a search for more sustainable and environmentally friendly methods of ammonia production. One such method is the use of renewable electricity to power an electrolyzer, which can produce hydrogen and oxygen. However, the integration of this technology into existing ammonia production plants presents its own set of challenges, including the need for additional equipment and modifications to existing infrastructure. Additionally, the use of electrolyzers also raises issues related to the management of the produced hydrogen and oxygen, as well as the overall efficiency of the process. In accordance with embodiments, a method is provided for revamp of an existing ammonia or urea plant comprising an existing primary and secondary steam reforming unit for the preparation of ammonia synthesis gas and an ammonia synthesis loop. The method includes adding an electrolysis unit to produce hydrogen and oxygen, adding an autothermal reformer in parallel to the existing primary and secondary reforming unit, installing a feed pipe connected to the autothermal reformer for supplying a hydrocarbon feed, installing a further feed pipe connected to the autothermal reformer and to electrolysis unit for supplying at least a part of the oxygen produced in the electrolysis unit, installing a pipe connecting outlet of the autothermal reforming unit and outlet of the secondary reforming unit, and installing a hydrogen supply pipe connecting the electrolysis unit with suction side of a synthesis gas compressor upstream the existing ammonia loop.

[0005] In accordance with other embodiments, a method is provided for decarbonizing an am- monia / urea plant. The method includes using an electrolyzer powered by renewable electricity to produce green hydrogen and oxygen, adding the green hydrogen to the suction of a synthesis gas compressor, using the oxygen for autothermal reforming in an Autothermal Reformer (ATR) installed parallel to an existing reforming section, and reducing fuel consumption in a primary reformer, thereby reducing carbon emissions.

[0006] In summary, the preferred embodiments of the method according to the invention are as follows:

[0007] 1 . A method for revamp of an existing ammonia or urea plant comprising an existing primary and secondary steam reforming unit for the preparation of ammonia synthesis gas and an ammonia synthesis loop, the method comprises a) adding an electrolysis unit to produce hydrogen and oxygen; b) adding an autothermal reformer in parallel to the existing primary and secondary reforming unit; c) installing a feed means connected to the autothermal reformer for supplying a hydrocarbon feed; d) installing a further feed means connected to the autothermal reformer and to electrolysis unit for supplying at least a part of the oxygen produced in the electrolysis unit; e) installing a means for connecting outlet of the autothermal reforming unit and outlet of the secondary reforming unit; and f) installing a hydrogen supply means, connecting the electrolysis unit with suction side of a synthesis gas compressor upstream the existing ammonia loop.

[0008] 2. A method for decarbonizing an ammonia / urea plant, the method comprising:

[0009] - using an electrolyzer powered by renewable electricity to produce green hydrogen and oxygen;

[0010] - adding the green hydrogen to the suction of a synthesis gas compressor;

[0011] - using the oxygen for autothermal reforming in an Autothermal Reformer (ATR) installed parallel to an existing reforming section;

[0012] - reducing fuel consumption in a primary reformer, thereby reducing carbon emissions.

[0013] 3. The method of embodiment 1or 2, further comprising diverting approximately 50% of Natural Gas (NG) feed to the ATR at minimum turndown operation of the primary reformer.

[0014] 4. The method of embodiment 1 or 2, wherein the electrolyzer is selected from the group consisting of Solid Oxide Electrolysis Cell (SOEC), Alkaline, and Proton Exchange Membrane (PEM).

[0015] 5. The method of embodiment 1 or 2, further comprising installing a prereformer upstream of the ATR.

[0016] 6. The method of embodiment 1 or 2, further comprising installing electrical heaters to obtain needed duties. 7. The method of embodiment 1 or 2, further comprising using excess green hydrogen as fuel in the primary reformer.

[0017] 8. The method of embodiment 1 or 2, wherein the carbon emissions from the primary reformer are reduced by approximately 65%.

[0018] The different steps according to a specific embodiment of the invention are as follows: Adding an electrolysis unit : This step involves installing an electrolyzer that uses renewable electricity to split water into hydrogen and oxygen. The hydrogen produced is for ammonia synthesis, and the oxygen is for the autothermal reforming process.

[0019] Adding an autothermal reformer in parallel : An autothermal reformer is installed in parallel to the existing primary and secondary reforming units. The ATR uses oxygen and heat to convert hydrocarbons into synthesis gas. This installation allows for a more efficient synthesis gas production process and reduces the load on the primary reformer. Installing a feed means, e.g. a pipe for hydrocarbon feed: A feed means is installed to supply natural gas to the ATR. This means e.g. a pipe directs a portion of the natural gas feedstock to the ATR for reforming into synthesis gas.

[0020] Installing a feed means e.g. a pipe for oxygen supply: Another feed means is installed to supply oxygen produced by the electrolysis unit to the ATR. This oxygen is necessary for the autothermal reforming process within the ATR.

[0021] Connecting the ATR and secondary reforming unit : Any suitable means, e.g. a pipe is installed to connect the outlet of the ATR with the outlet of the secondary reforming unit. This allows the synthesis gas produced by the ATR to be combined with the gas from the secondary reformer.

[0022] Installing a means for hydrogen supply, e.g a pipe : A hydrogen supply pipe is installed to connect the electrolysis unit with the suction side of a synthesis gas compressor upstream of the ammonia loop. This pipe introduces the hydrogen into the ammonia synthesis process. In summary, all steps include the integration of an electrolysis unit to produce hydrogen and oxygen, the addition of an ATR to work alongside existing reforming units, and the installation of necessary infrastructure, e.g. piping, to supply feedstocks and connect the new and existing components of the plant. These actions are aimed at modernizing the plant and reducing carbon emission of the ammonia synthesis process.

[0023] The steps encompass a method for reducing carbon emissions in an ammonia / urea plant. This method involves the operation of an electrolyzer that utilizes renewable electricity to generate hydrogen and oxygen. The hydrogen is then directed to the suction side of a synthesis gas compressor, which is part of the process for producing ammonia synthesis gas.

[0024] Concurrently, the oxygen from the electrolyzer is supplied to an Autothermal Reformer (ATR) that is installed alongside the existing reforming section of the plant. The ATR employs this oxygen and a hydrocarbon feed, delivered through a dedicated feed means e.g. a pipe, to produce synthesis gas via autothermal reforming. This process decreases the fuel requirement for the primary reformer, leading to a reduction in carbon dioxide output.

[0025] Additionally, the steps involve the adjustment of natural gas flow, directing a portion to the ATR when the primary reformer is operating at its lowest capacity. This ensures efficient use of the ATR and maintains the operation of the primary reformer.

[0026] The method also optionally includes the installation of a prereformer, positioned upstream the ATR. The prereformer treats the hydrocarbons before they enter the ATR, improving the reforming process's efficiency. To meet the heat requirements of the plant, electrical heaters are installed.

[0027] If there is surplus hydrogen produced by the electrolyzer, it is used as a fuel source for the primary reformer. This use of hydrogen contributes to the overall reduction of carbon emissions. The collective implementation of these steps results in a decrease in carbon emissions from the primary reformer, with an approximate reduction of 65%. This decrease is attributed to the integration of hydrogen into the ammonia synthesis process, the optimization of the ATR's operation, and the enhanced efficiency of the plant's reforming pro- cesses.

Claims

Claims:1 . A method for revamp of an existing ammonia or urea plant comprising an existing primary and secondary steam reforming unit for the preparation of ammonia synthesis gas and an ammonia synthesis loop, the method comprises a) adding an electrolysis unit to produce hydrogen and oxygen; b) adding an autothermal reformer in parallel to the existing primary and secondary reforming unit; c) installing a feed means connected to the autothermal reformer for supplying a hydrocarbon feed; d) installing a further feed means connected to the autothermal reformer and to electrolysis unit for supplying at least a part of the oxygen produced in the electrolysis unit; e) installing a means for connecting outlet of the autothermal reforming unit and outlet of the secondary reforming unit; and f) installing a hydrogen supply means connecting the electrolysis unit with suction side of a synthesis gas compressor upstream the existing ammonia loop.

2. A method for decarbonizing an ammonia / urea plant, the method comprising:- using an electrolyzer powered by renewable electricity to produce green hydrogen and oxygen;- adding the green hydrogen to the suction of a synthesis gas compressor;- using the oxygen for autothermal reforming in an Autothermal Reformer (ATR) installed parallel to an existing reforming section;- reducing fuel consumption in a primary reformer, thereby reducing carbon emissions.

3. The method of claim 1 or 2, further comprising diverting approximately 50% of Natural Gas (NG) feed to the ATR at minimum turndown operation of the primary reformer.

4. The method of claim 1 or 2, wherein the electrolyzer is selected from the group consisting of Solid Oxide Electrolysis Cell (SOEC), Alkaline, and Proton Exchange Membrane (PEM).

5. The method of claim 1 or 2, further comprising installing a prereformer upstream of the ATR.

6. The method of claim 1 or 2, further comprising installing electrical heaters to obtain needed duties.

7. The method of claim 1 or 2, further comprising using excess green hydrogen as fuel in the primary reformer.

8. The method of claim 1 or 2, wherein the carbon emissions from the primary reformer are reduced by approximately 65%.