US-20260126004-A1 - SYSTEM AND METHOD FOR PRODUCING AMMONIA

US20260126004A1US 20260126004 A1US20260126004 A1US 20260126004A1US-20260126004-A1

Abstract

A system for manufacturing ammonia, having an ammonia reactor which is designed to produce ammonia (NH3) from a synthesis gas, the synthesis gas including hydrogen (H 2 ) and nitrogen (N2), further including an electrolizer which is designed to produce hydrogen and oxygen from water, where a compressor is fluidically connected to the electrolizer and is designed to compress the hydrogen (H2) coming from the electrolizer, wherein the compressor is designed to compress transportable hydrogen (H2).

Inventors

Suhel Ahmad
Peter Adam
Lukas Biyikli

Assignees

Siemens Energy Global GmbH & Co. KG

Dates

Publication Date: 20260507
Application Date: 20230905
Priority Date: 20220930

Claims (17)

1 . A system for manufacturing ammonia, comprising an ammonia reactor which is designed to produce ammonia (NH 3 ) from a synthesis gas, the synthesis gas comprising hydrogen (H 2 ) and nitrogen (N 2 ); and further comprising an electrolizer which is designed to produce hydrogen and oxygen from water, wherein a compressor which is fluidically connected to the electrolizer and is designed to compress the hydrogen (H 2 ) coming from the electrolizer, and wherein the compressor is designed to compress hydrogen (H 2 ).
2 . The system according to claim 1 , wherein the compressed hydrogen (H 2 ) is suitable for transport in a pipeline.
3 . The system according to claim 1 , wherein the electrolizer is operated with renewable energies.
4 . The system according to claim 1 , further comprising a gas turbine operated with hydrogen (H 2 ), wherein the hydrogen (H 2 ) produced from the electrolizer is mixed with the nitrogen (N2) produced from an exhaust gas of the gas turbine to produce the synthesis gas.
5 . The system according to claim 4 , further comprising a heat exchanger which is designed to produce steam from a thermal energy of the exhaust gas of the gas turbine, wherein a steam turbine is provided which is charged with the steam from the heat exchanger.
6 . The system according to claim 5 , further comprising a generator which is coupled to the steam turbine in a torque-transmitting manner.
7 . The system according to claim 6 , further comprising a separation unit-which is designed to separate an exhaust gas from the gas turbine into nitrogen and water, wherein the nitrogen is employed for the synthesis gas, wherein the water is supplied to the heat exchanger.
8 . The system according to claim 1 , further comprising an oxygen line for oxygen which was obtained from the electrolizer, further comprising an expander, wherein the oxygen from the oxygen line is fluidically connected to the expander, wherein, in the expander, a pressure energy of the oxygen from the oxygen line is converted into mechanical energy.
9 . The system according to claim 8 , further comprising a heat exchanger which is designed such that the oxygen flowing out of the expander cools a coolant of the electrolysis.
10 . The system according claim 1 , wherein the electrolizer is coolable with a coolant, wherein the system comprises a heat pump circuit which is designed to cool the coolant.
11 . The system according to claim 10 , further comprising a heat exchanger which is fluidically connected to the oxygen line, wherein the heat exchanger is designed such that a thermal energy of the coolant located in the heat pump circuit is transferrable to the oxygen.
12 . A method for manufacturing ammonia, wherein, in an ammonia reactor, ammonia (NH3) is produced from a synthesis gas, the synthesis gas comprising hydrogen (H2) and nitrogen (N2), wherein, in an electrolizer, hydrogen and oxygen are produced using renewable energies, wherein the hydrogen produced in the electrolizer is compressed in a compressor.
13 . The method according to claim 12 , wherein the hydrogen compressed in the compressor is employed for transport.
14 . The method according to claim 12 , wherein an expander is used which is operated with a heated oxygen from a heat exchanger.
15 . The method according to claim 12 , wherein a generator is employed which is operated with an expander, wherein the generator is designed to produce electrical energy.
16 . The method according to claim 12 , wherein a separation unit is used with which an exhaust gas from a gas turbine is separated into nitrogen and water.
17 . The method according to claim 12 , wherein a coolant is used for cooling the electrolizer, wherein the coolant is cooled down with a heat pump circuit.

Description

BACKGROUND The invention relates to a system for manufacturing ammonia, comprising an ammonia reactor which is designed to produce ammonia (NH3) from a synthesis gas, the synthesis gas comprising hydrogen (H2) and nitrogen (N2), further comprising an electrolizer which is designed to produce hydrogen (H2) and oxygen (O2) from water. Moreover, the invention relates to a method for manufacturing ammonia, wherein, in an ammonia reactor, ammonia (NH3) is produced from a synthesis gas, the synthesis gas comprising hydrogen (H2) and nitrogen (N2), wherein, in an electrolizer, hydrogen (H2) and oxygen (O2) are produced using renewable energies. The invention proposes a concept for an ammonia system comprising an electrolizer which is operated with renewable energies, wherein cooling and heating in the system is via a chiller or a heat pump, wherein the system employs a gas turbine operated with hydrogen, wherein the gas turbine makes nitrogen available for ammonia manufacture. The production of ammonia goes back to a known method which typically requires very much energy. According to first estimations, currently about 1% of the energy produced worldwide are required for the manufacture of ammonia. The ammonia produced from green hydrogen is referred to as green ammonia. Green ammonia is regarded as a fast-growing energy carrier for hydrogen. Furthermore, it is used in many industrial processes, especially in fertilizers. It is estimated that approx. 50% of the green hydrogen which will be produced in the next years will be directly processed to liquid ammonia for long-distance transport of hydrogen as the liquefaction of pure hydrogen is very energy-intensive. The largest energy and compression expenditure, in addition to the hydrogen production through electrolysis and the nitrogen production through air separation systems, is synthesis gas compression, which compresses the nitrogen-hydrogen mixture to the pressure of 150-220 bar required for the synthesis process, and the cold box, which provides the cooling energy for the liquefaction and cooling of the ammonia to approx. −33° C. at atmospheric pressure. Typically, a pre-heating unit for heating the synthesis gas to the reaction temperature is required. Ammonia is an important chemical used most notably in the fertilizer industry. The ammonia reaction is the catalytic reaction of hydrogen and nitrogen at high temperature and high pressure. However, the manufacture of hydrogen accounts for the largest part of energy consumption and about 90% of carbon emissions. Hydrogen is produced almost exclusively by steam reforming of fossil fuels. Most ammonia systems utilize steam reforming of natural gas to produce hydrogen and carbon dioxide. Coal, heavy fuel oil, and naphtha may also be used but have higher carbon dioxide emissions. Consequently, ammonia production with these methods causes almost 1.5% of worldwide CO2 emissions. The nitrogen is obtained from compressed air or from an air separation system. At present, the nitrogen and hydrogen required for the ammonia manufacture are usually compressed to the required synthesis pressure in a synthesis gas compressor. The suction pressure for this compressor is typically determined by the hydrogen pressure which in case of green ammonia applications, where electrolysis is carried out on site, is limited to the maximum starting pressure of an electrolysis system (max. 30-40 bar). The shaft power for the compressor is delivered by a steam turbine, while the required steam is produced through the heat which is released during the ammonia synthesis. Pre-warming of the synthesis gas must be either through a fuel-fired or electricity-fired heater or through utilization of waste heat of the ammonia process, which reduces the amount of the steam produceable for the steam turbine. Liquefaction is via a refrigerant circuit. With commitments made to achieve net-zero emissions targets, new zero-carbon fuels such as green ammonia and green hydrogen are needed to decarbonize energy production, heat supply, traffic and industry. It is estimated that approx. 50% of the green hydrogen which will be produced in the next years will be converted into green ammonia. Ammonia can be used as a convenient hydrogen energy carrier and the already existing industry, which produces, stores and trades millions of tons of ammonia every year, means that the infrastructure and the technology are already existent in order to launch the hydrogen economy. In conventional ammonia manufacture, the hydrogen gas (H2) is obtained from steam methane reforming (SMR), the most common method for the production of hydrogen, and the nitrogen gas (N2) is either obtained from air or from an air separation system. Nitrogen (N2) and hydrogen (H2) are mixed stoichiometrically (1:3) and compressed with a syngas compressor and guided into an ammonia synthesis reactor at a pressure of 150 to 220 bar. The ammonia synthesis gas reactor operates at an operating temperature o