Method for production of blue ammonia

Abstract

An ammonia plant is provided in which heat exchangers for steam generation (HP and or MP steam) and / or steam superheating (with process streams) are arranged downstream the ATR section, and between the high temperature (HT) shift section and a subsequent second shift section. In this manner, less steam is generated in the front end and less steam superheating is required in the fired steam superheater due to the partly steam superheating in the process cooling train.

Description

[0001] METHOD FOR PRODUCTION OF BLUE AMMONIA

[0002] TECHNICAL FIELD

[0003] The present invention relates to an ammonia plant and process for production of ammonia, in which heat exchangers for steam generation and / or steam superheating are arranged downstream the ATR section, between the high temperature (HT) shift section and a second shift section (either low temperature (LT) or alternatively medium temperature (MT) shift section), and in the ammonia synthesis loop downstream the ammonia converter. The method and system of the invention may be used in any ammonia plant.

[0004] BACKGROUND

[0005] Blue ammonia is a fossil fuel-based product produced with minimum emission of CO2 to the atmosphere. It is seen as a transition product between conventional fossil fuel-based ammonia and green ammonia produced from green or renewable power, water and air. The CO2 resulting from a blue ammonia production shall be stored permanently or converted into other chemicals. The main steps for producing blue ammonia are essentially the same as for producing conventional fossil fuel-based ammonia, the difference being that more of the carbon stemming from the carbon fuel is captured, providing a possibility for further processing.

[0006] The key here is that the blue ammonia does not release any carbon dioxide when used as fertilizer or burned . Currently available technology traps nearly all CO2 generated during the conversion process making this fuel one of the first carbon free fuel options for mass use. Blue ammonia is considered an environmentally friendly product which can be used until sufficient renewable or green power is available for producing green ammonia.

[0007] Utility prices vary dependent on plant / site location. The blue ammonia layout that becomes the most optimal and attractive varies for given specific utility prices. It may also be desirable to avoid, or reduce the need for, a fired steam superheater.

[0008] Known technology within this field is described in WO2018 / 149641, PCT / EP2022 / 059091 and PCT / EP2023 / 061637. SUMMARY

[0009] An ammonia plant is provided said plant comprising : a hydrocarbon feed; a burner steam feed; a process steam feed; an oxygen feed; a nitrogen feed; boiler feed water; a feed pre-heater being arranged to pre-heat the hydrocarbon feed to generate a preheated hydrocarbon feed; a feed purification section, being arranged to hydrogenate and remove sulfur compounds from the preheated hydrocarbon feed, and to generate a purified hydrocarbon feed; a prereformer feed preheater arranged to heat a combined stream comprising purified hydrocarbon feed and process steam feed and to generate a heated combined stream; a prereforming section arranged to pre-reform the heated combined stream from the prereformer feed preheater and to generate a first process gas stream; a process gas pre-heater arranged to heat said first process gas stream and to generate a heated first process gas stream; an autothermal reforming ATR section arranged to receive at least a portion of the heated first process gas stream, said oxygen feed and said burner steam feed and to generate a second process gas stream; a steam drum arranged to receive boiler feed water and supply a first boiler water stream and a second boiler water stream; a first waste heat boiler (WHB) arranged to heat exchange at least a portion of the second process gas stream with the first boiler water stream from said steam drum and generate a cooled second process gas stream and a first steam stream; a high temperature (HT) shift section arranged to receive the cooled second process gas stream from the first waste heat boiler and generate a third process gas stream; a second waste heat boiler arranged to heat exchange at least a portion of the third process gas stream with a second boiler water stream from said steam drum, and generate a cooled third process gas stream and a second steam stream; and / or a steam superheater arranged to heat exchange at least a portion of the third process gas stream with a steam stream from said steam drum, and generate a cooled third process gas stream and a superheated steam stream; provided that, when the ammonia plant comprises a second waste heat boiler and a steam superheater, the third process gas stream is arranged to be fed to the steam superheater and cooled to a third process gas stream which is then arranged to be fed to the second waste heat boiler and cooled to a further cooled third process gas stream; a second shift section arranged to receive the cooled third process gas stream(s) and generate a fourth process gas stream; a second shift section arranged to receive the third process gas stream and generate a fourth process gas stream; a syngas purification section arranged to receive said fourth process gas stream and said nitrogen feed and to generate a syngas stream comprising hydrogen and nitrogen (e.g. in the ratio 3: 1), a CC -rich stream, a process condensate, and at least one off-gas stream; an ammonia synthesis loop arranged to receive the syngas stream and to generate a first ammonia-rich stream.

[0010] A process for generating ammonia in the ammonia plant described herein is also provided.

[0011] Further details of the plant and process are specified in the following detailed description, figures and claims.

[0012] LEGENDS

[0013] Fig. 1 shows a layout of an ammonia plant according to the invention.

[0014] Fig. 2 shows an alternative layout of an ammonia plant according to the invention.

[0015] Fig. 3 shows a layout of a syngas purification section and ammonia loop, which can be used in the ammonia plants illustrated in Figures 1 and 2.

[0016] Fig. 4 shows a layout of an ammonia plant, based on the combined layouts of Figures 1 and 2.

[0017] Fig. 5 shows when the different steam generation systems become attractive with respect to natural gas and power prices,

[0018] Figure 6 shows a layout of an ammonia plant, developed from the layout of Figure 4, designed for maximum HP steam generation Figures 7, 8 and 9 show various layouts of the ammonia plant according to the invention.

[0019] Figure 7 is a layout used to achieve reduced HP steam generation

[0020] Figure 8 is a layout used to achieve reduced HP steam generation in the front-end and MP steam generation in the loop.

[0021] Figure 9 is a layout used to achieve superheated MP steam generation in the front-end and loop. No fired steam superheater is needed.

[0022] DETAILED DISCLOSURE

[0023] Unless otherwise specified, any given percentages for gas content are % by volume. The terms "synthesis gas" and "syngas" are used interchangeably in this text.

[0024] An ammonia plant (A) is provided. The feeds inputted to the plant comprise: a hydrocarbon feed (typically natural gas or biogas) a burner steam feed; a process steam feed; an oxygen feed; a nitrogen feed; and boiler feed water.

[0025] A feed pre-heater is arranged to pre-heat the hydrocarbon feed and to generate a pre-heated hydrocarbon feed. Typical temperatures of the preheated hydrocarbon feed are between 350 and 400°C. Preheating of the hydrocarbon feed may take place in a heater coil within a fired heater. Alternatively, the feed pre-heater may be an electrical heater.

[0026] In one aspect, the feed pre-heater may be arranged to pre-heat the hydrocarbon feed via heat exchange with at least a portion of the second steam stream. Advantageously, it would then be possible to reduce the size of the fired process heater as well. To reach the necessary preheat temperatures for the process streams will require that steam temperatures are sufficiently high for preheating. If superheated HP steam is generated the temperature of the superheated HP steam is typically 510 °C and for superheated MP steam it is typically 380 °C. This sets the limit for preheating the process streams with steam. A feed purification section is arranged to hydrogenate and remove sulfur compounds from the preheated hydrocarbon feed, and to generate a purified hydrocarbon feed. The feed purification section suitably comprises a hydrogenation unit upstream a sulfur removal unit. Hydrogenation removes any unsaturated components of the hydrocarbon feed. Both unsaturated components of the hydrocarbon feed and sulfur components may contaminate downstream catalysts in the ammonia plant.

[0027] The purified hydrocarbon feed is combined with process steam feed and then heated again in a prereformer feed preheater to generate a heated combined stream. Typical temperatures of the heated combined stream are between 400 and 550°C. The prereformer feed preheater may comprise a heater coil within a fired heater, in a similar manner to the feed pre-heater mentioned above.

[0028] The heated combined stream is fed to prereforming section, which is arranged to pre-reform the heated combined stream and to generate a first process gas stream. Pre-reforming is the process by which methane and heavier hydrocarbons are steam reformed and the products of the heavier hydrocarbon reforming are methanated. Typically, a nickel-containing catalyst is used. Pre-reforming sections suitable for this process are known to the person skilled in the art.

[0029] First process gas stream is then fed to a process gas pre-heater which is arranged to heat this first process gas stream and to generate a heated first process gas stream. Typical temperatures of the heated first process gas stream are between 350 and 650 °C.

[0030] The plant comprises an autothermal reforming ATR. section arranged to receive at least a portion of the heated first process gas stream, the oxygen feed and the burner steam feed and to generate a second process gas stream. Autothermal reforming sections, catalysts and conditions are known to the person skilled in the art.

[0031] The ammonia plant comprises a steam drum. The steam drum is arranged to receive boiler feed water and supply a first boiler water stream and a second boiler water stream. The steam drum is - in one aspect - arranged to receive at least the first steam stream from said first waste heat boiler, and optionally the second steam stream from said second heat exchanger (in the case where this is a waste heat boiler). The stream drum may also receive steam from the heat exchanger in the ammonia loop.

[0032] Suitably, the second boiler water stream is in the form of a water stream, and the steam drum is also arranged to receive at least the first steam stream from the first waste heat boiler, and the second steam stream from the second heat exchanger. The ammonia plant further comprises a fired steam superheater arranged to receive a saturated steam stream from said steam drum and to superheat it to provide a superheated steam stream. The fired superheater has a fuel stream. The fuel for the fired heater and the fired steam superheater are suitably a combination of the off gases from the plant, and natural gas. Steam superheating in the fired steam superheater also takes place in coil(s).

[0033] Steam generation (superheated HP steam and / or superheated MP steam in front end and the loop) can either be minimized or maximized dependent on actual utility prices and what will be the most attractive to do in a given situation. Medium pressure steam generation in front end and loop and steam superheating after the first shift reactor in the process cooling train is attractive for high natural gas prices and / or low power prices. Maximum steam generation is attractive for low natural gas prices and / or high power prices. By replacing the waste heat boiler downstream the first shift reactor with a steam superheater, less steam is being generated in the front end and less steam superheating is required in the fired steam heater due to the partly steam superheating in the process cooling train. The size of the fired steam super heater duty is thereby reduced and in case of MP steam is generated in front end and loop a fired steam superheater is even avoided. Also, a layout with high front end pressure in the Blue ammonia process is found attractive for a wide range of utility prices.

[0034] A first waste heat boiler is arranged to heat exchange at least a portion of the second process gas stream with the first boiler water stream from the steam drum and generate a cooled second process gas stream and a first steam stream. The first steam stream is fed back to the steam drum.

[0035] A high temperature (HT) shift section is arranged to receive the cooled second process gas stream from the first waste heat boiler and generate a third process gas stream. By means of the shift sections, the desired composition of the syngas can be achieved. Shift means Water-gas shift reaction (WGSR) or Shift reaction, the reaction of carbon monoxide and water vapor to form carbon dioxide and hydrogen:

[0036] CO + H2O CO2 + H2

[0037] The WGSR is an important industrial reaction that is used in the manufacture of ammonia, hydrocarbons, methanol, and hydrogen. It is also often used in conjunction with steam reforming of methane and other hydrocarbons. In the Fischer-Tropsch process, the WGSR is one of the most important reactions used to balance the H2 / CO ratio. The water gas shift reaction is a moderately exothermic reversible reaction. Therefore, with increasing temperature the reaction rate increases but the carbon dioxide production becomes less favourable. Due to its exothermic nature, high carbon monoxide percentage is thermodynamically favoured at low temperatures. Despite the thermodynamic favourability at low temperatures, the reaction is faster at high temperatures.

[0038] A second waste heat boiler is located downstream the HT shift section, and is arranged to heat exchange at least a portion of the third process gas stream with the second boiler water stream from said steam drum. A cooled third process gas stream and a second steam stream are thus generated. The second steam stream is fed back to the steam drum.

[0039] Alternatively or additionally, a steam superheater is arranged to heat exchange at least a portion of the third process gas stream with a steam stream from the steam drum, so as to generate a cooled third process gas stream and a superheated steam stream. In case of steam generation and steam superheating downstream the HT shift section the steam superheater is located upstream of the second waste heat boiler. In other words, when the ammonia plant comprises a second waste heat boiler and a steam superheater, the third process gas stream is arranged to be fed to the steam superheater and cooled to a third process gas stream which is then arranged to be fed to the second waste heat boiler and cooled to a further cooled third process gas stream.

[0040] Subsequently, a second shift section is arranged to receive the third process gas stream and generate a fourth process gas stream. The second shift section may be a low temperature (LT) or a medium temperature (MT) shift section, and is preferably a low temperature shift section. LT shift typically takes place at temperatures between process gas Tdew+ 15°C and 250°C, while MT shift typically takes place between 190 - 330°C. At this point, CO is shifted to a minimum to maximize H2 production and to increase process carbon capture.

[0041] A syngas purification section is arranged to receive the fourth process gas stream and the nitrogen feed and to generate a syngas stream comprising hydrogen and nitrogen (e.g. in the ratio 3: 1), and : a CO2-rich stream, a process condensate, and one or more off-gas stream(s). Suitably, the syngas purification section generates a syngas stream, a CCh-rich stream, a process condensate, and one or more off-gas stream(s).

[0042] In one aspect, the syngas purification section comprises a separator, a CO2 removal unit and a hydrogen purification unit. It may be possible that the syngas purification section comprises a separator, a hydrogen purification unit and a CO2 removal unit, in this order. The separator is typically arranged to receive said fourth process gas stream and generate a dried fourth process gas stream and a process condensate. In the first aspect the CO2 removal unit is arranged to receive the dried fourth process gas stream and to generate a CC -rich stream and a CC -depleted fourth process gas stream. The hydrogen purification unit is arranged to receive the CC -depleted fourth process gas stream and to generate the syngas stream comprising hydrogen and nitrogen (e.g. in the ratio 3: 1), and an off-gas stream. In a further aspect the hydrogen purification unit is arranged to receive the dried fourth syngas (or process gas) stream and to generate a hydrogen product stream, one or more hydrogen rich fuel stream(s) and a CO2 rich off gas stream. The CO2 removal section is arranged to receive the CO2 rich off gas stream and to generate a CO2 product stream and an off-gas stream which is further sent to one or more PSA units to generate hydrogen rich fuel stream(s) and a carbon rich stream. The latter is to be recycled to the ATR.

[0043] In an alternative aspect, the syngas purification section comprises, in order: separator, hydrogen purification unit and CO2 removal unit. This arrangement provides that fourth process gas stream passes first through the separator, then through the hydrogen purification unit and then through the CO2 removal unit.

[0044] In a further aspect, shown in Figure 4, the hydrogen purification unit, arranged downstream the CO2 removal section, is arranged to generate the off-gas stream, and at least a first portion of the off-gas stream is arranged to be compressed in a compressor and combined with the first process gas stream, upstream the ATR section.

[0045] It is also possible that at least a second portion of the off-gas stream is arranged to be fed as fuel to the fired heater, optionally in combination with a portion of the syngas stream.

[0046] An ammonia synthesis loop is arranged to receive the syngas stream and to generate a first ammonia-rich stream. In a standard layout, the ammonia synthesis loop comprises an ammonia reactor, a recycle compressor, an ammonia separator and at least one heat exchanger arranged downstream the ammonia separator. Suitably, a third boiler water stream is arranged to be heat exchanged in said at least one heat exchanger.

[0047] In one aspect, the ammonia plant comprises a fired heater and a fuel stream for said fired heater. At least one - and preferably all - of said feed pre-heater, prereformer feed preheater and syngas pre-heater comprise a heater coil within said fired heater. Advantageously, a portion of the syngas stream comprising hydrogen and nitrogen is arranged to be fed as fuel to the fired heater.

[0048] A process is also provided for generating ammonia in the ammonia plant (A) described herein, said process comprising the steps of: providing the plant as described herein, pre-heating the hydrocarbon feed in the feed pre-heater and generating a pre-heated hydrocarbon feed; hydrogenating and removing sulfur compounds from the preheated hydrocarbon feed in the feed purification section, and generating a purified hydrocarbon feed; heating a combined stream comprising purified hydrocarbon feed and process steam feed in the prereformer feed preheater and generating a heated combined stream; pre-reform the heated combined stream from the prereformer feed preheater in the prereforming section and generating a first process gas stream; heating the first process gas stream in the syngas pre-heater and generating a heated first process gas stream; feeding at least a portion of the heated first process gas stream, said oxygen feed and said burner steam feed to the autothermal reforming ATR. section and generating a second process gas stream; feeding boiler feed water to the steam drum supplying a first boiler water stream and a second boiler water stream; heat exchanging at least a portion of the second process gas stream with a first boiler water stream from said steam drum in the first waste heat boiler (WHB) and generating a cooled second process gas stream and a first steam stream; feeding the cooled second process gas stream from the first waste heat boiler to the high temperature (HT) shift section and generating a third process gas stream; heat exchanging at least a portion of the third process gas stream with a second boiler water stream from said steam drum in the second waste heat boiler and generating a cooled third process gas stream and a second steam stream; and / or heat exchanging at least a portion of the third process gas stream with a steam stream from said steam drum in the steam superheater and generating a cooled third process gas stream and a superheated steam stream; provided that, when the ammonia plant comprises a second waste heat boiler and a steam superheater, the third process gas stream is fed to the steam superheater and cooled to a third process gas stream which is then fed to the second waste heat boiler and cooled to a further cooled third process gas stream; feeding the cooled third process gas stream(s) to the second shift section and generating a fourth process gas stream; feeding the fourth process gas stream and said nitrogen feed to the syngas purification section and generating a syngas stream comprising hydrogen and nitrogen (e.g. in the ratio 3: 1), and at least one of: a CCh-rich stream, a process condensate and one or more off-gas stream(s); feeding the syngas stream to the ammonia synthesis loop and generating a first ammonia-rich stream. Specific embodiments

[0049] Figure 1 shows a layout of an ammonia plant according to the invention, with the following features: hydrocarbon feed (1) burner steam feed (2') process steam feed (2) oxygen feed (3) nitrogen feed (4) boiler feed water (8) feed pre-heater (91) pre-heated hydrocarbon feed (1') feed purification section (80) purified hydrocarbon feed (1") prereformer feed preheater (92) combined stream (81) comprising purified hydrocarbon feed (1") and process steam feed (2) heated combined stream (81') hydrogenation unit (82) sulfur removal unit (83) prereforming section (20) first process gas stream (21) syngas pre-heater (93) heated first process gas stream (21') autothermal reforming ATR. section (30) second process gas stream (31) steam drum (110) first boiler water stream (112) second boiler water stream (113) a first waste heat boiler (40) cooled second process gas stream (31') first steam stream (41) high temperature (HT) shift section (50) third process gas stream (51) waste heat boiler (70) cooled third process gas stream (51') second steam stream (71) second (e.g. low temperature (LT)) shift section (60) fourth process gas stream (61) fired heater (90) fuel stream (9) for the fired heater and fired SSH syngas purification section (100) syngas stream (104) comprising hydrogen and nitrogen,

[0050] CC -rich stream (101) process condensate (102) off-gas stream (151) (one or more) ammonia synthesis loop (200) first ammonia-rich stream (201) fired steam superheater (120) saturated steam stream (111) superheated steam stream (121)

[0051] In figure 2, corresponding elements have the same reference numerals as those in figure 1. Additional references are: steam superheater (75) superheated steam stream (115') steam stream (115)

[0052] Fig. 3 shows a layout of a syngas purification section and ammonia loop, which can be used in the ammonia plants illustrated in Figures 1 and 2. Additional references are: separator (130) dried fourth process gas stream (131) process condensate (102)

[0053] CO2 removal unit (140)

[0054] CO2-rich stream (101)

[0055] CC -depleted fourth process gas stream (141) hydrogen purification unit (150) off-gas stream(s) (151) ammonia reactor (240) recycle compressor (220) ammonia separator (230) heat exchanger(s) (250) syngas streams (231, 221 241) Fig. 4 shows a layout of an ammonia plant, based on the combined layouts of Figures 1 and 2. Additional references are: offgas stream (151), first portion (151A) of the offgas stream (151) off gas recycle compressor (160) a second portion (151B) of offgas stream (151) compressed off gas (161)

[0056] Fig. 6 shows a layout of an ammonia plant, developed from the layout of Figure 4. Additional references are: third boiler water stream (114) third steam stream (114')

[0057] Fig. 7 shows a layout of an ammonia plant, similar to that of Fig. 6, with the addition that the partly superheated steam stream (115') from the steam superheater (75) is passed through fired superheater (120) to provide a further superheated steam stream (121).

[0058] Fig. 8 shows a layout of an ammonia plant, similar to that of Fig. 7, in which the ammonia loop comprises a loop waste heat boiler (250), a loop steam drum (260) arranged to provide superheated medium-pressure steam stream (261) via heat exchange of a water stream with one or more, e.g. two heat exchangers (251) in the ammonia loop. The last heat exchanger it is passing in the loop is a steam superheater (252).

[0059] Figure 9 shows a layout similar to that of Figure 8, in which superheated steam stream (115') from the steam superheater (75) is not passed through further steam superheater (120). A fired steam superheater (120) is not needed since the steam is being fully superheated in steam superheater (75).

[0060] EXAMPLE

[0061] Figure 5 shows when the different steam generation systems become attractive with respect to natural gas and power prices, for example when the values in the following Table 1 apply as basis and then either natural gas or power price is varied :

[0062] Table 1 :

[0063] Example 1

[0064] Table 2 shows the benefits of the proposed layouts, in terms of consumption figures, CAPEX, specific carbon emission and carbon capture or recovery. Traditional ammonia production involves typically maximum HP steam generation and superheating of steam to be utilized for process steam and for steam turbines.

[0065] Steam generation (HP steam and / or MP steam generation in front-end and loop) can be optimized i.e. either minimized or maximized dependent on actual utility prices and what will be the most attractive to do in a given situation. Power is imported to close the overall steam / power balance.

[0066] To meet 90 % carbon capture, the front end of the plant is increased to produce supplementary excess H2 flow to be used as fuel in the fired heaters / process furnaces (fired process preheater + fired steam superheater). The required front-end increase is shown in table 2 for the various steam generation configurations. The present invention provides the layout in the three last columns to the right in Table 2, showing results, for a 3000 MTPD blue ammonia plant with 90% carbon capture, going towards reducing the steam production by superheating steam utilizing the process heat to an increasing extent going from the reduced HP generation case to the reduced MP steam generation case in front-end and loop. Advantageously, in the latter case a fired steam superheater can be avoided. Instead, all steam superheating is performed in the process cooling train. The results show that consumption figures, specific CO2 emissions and CAPEX reduce, when compared to maximum HP steam generation as in traditional ammonia production.

[0067] It is seen in table 2 that MP steam generation in front-end and loop becomes the most attractive layout if low cost renewable power is available. This case, representing the minimum steam generation case, has the lowest NG (feed + fuel) consumption of all the cases and has an advantage as shown in figure 5 above a natural gas price of around 7C / MMBTU. In addition, it has the lowest CAPEX value. Power import requirement increases with reduced steam production and is highest for this case. This means that MP steam generation in front-end and loop becomes attractive at low power prices, below around 75 € / MWh as shown in figure 5.

[0068] In the three first cases a flash gas recycle is included in the CO2 removal section to maximize the CO2 capture from the process. For the last case (MP steam generation in front-end and loop) a carbon capture of 93% is obtained when including flash gas recycle in the CO2 removal section without the necessity of producing supplementary hydrogen fuel. To meet 90% carbon capture the flash gas from the CO2 removal section was therefore used as fuel to the fired heaters instead. This means that up to 93% carbon capture can be obtained in this case without increasing the front-end for supplementary hydrogen fuel production.

[0069] Table 2

[0070] The present invention has been described with reference to a number of aspects and figures. However, the skilled person is able to select and combine various aspects within the scope of the invention, which is defined by the appended claims. All documents referenced herein are incorporated by reference.

Claims

CLAIMS1. An ammonia plant (A) said plant (A) comprising : a hydrocarbon feed (1); a burner steam feed (2'); a process steam feed (2); an oxygen feed (3); a nitrogen feed (4); boiler feed water (8); a feed pre-heater (91) being arranged to pre-heat the hydrocarbon feed (1) and to generate a pre-heated hydrocarbon feed (1'); a feed purification section (80), being arranged to hydrogenate and remove sulfur compounds from the preheated hydrocarbon feed (1'), and to generate a purified hydrocarbon feed (1"); a prereformer feed preheater (92) arranged to heat a combined stream (81) comprising purified hydrocarbon feed (1") and process steam feed (2) and to generate a heated combined stream (81'); a prereforming section (20) arranged to pre-reform the heated combined stream (81') from the prereformer feed preheater (92) and to generate a first process gas stream (21); a process gas pre-heater (93) arranged to heat said first process gas stream (21) and to generate a heated first process gas stream (21') an autothermal reforming ATR. section (30) arranged to receive at least a portion of the heated first process gas stream (21'), said oxygen feed (3) and said burner steam feed (2') and to generate a second process gas stream (31); a steam drum (110) arranged to receive boiler feed water (8) and supply a first boiler water stream (112), a second boiler water stream (113), a first waste heat boiler (40) arranged to heat exchange at least a portion of the second process gas stream (31) with the first boiler water stream (112) from said steam drum (110) and generate a cooled second process gas stream (31') and a first steam stream (41); a high temperature (HT) shift section (50) arranged to receive the cooled second process gas stream (31') from the first waste heat boiler (40) and generate a third process gas stream (51); a second waste heat boiler (70) arranged to heat exchange at least a portion of the third process gas stream (51) with a second boiler water stream (113) from said steam drum (110), and generate a cooled third process gas stream (51') and a second steam stream (71); and / or a steam superheater (75) arranged to heatexchange at least a portion of the third process gas stream (51) with a steam stream (115) from said steam drum (110), and generate a cooled third process gas stream (51') and a superheated steam stream (115'); provided that, when the ammonia plant comprises a second waste heat boiler (70) and a steam superheater (75), the third process gas stream (51) is arranged to be fed to the steam superheater (75) and cooled to a third process gas stream (51') which is then arranged to be fed to the second waste heat boiler (70) and cooled to a further cooled third process gas stream (51"); a second shift section (60) arranged to receive the cooled third process gas stream(s) (51', 51") and generate a fourth process gas stream (61); a syngas purification section (100) arranged to receive said fourth process gas stream (61) and said nitrogen feed (4) and to generate a syngas stream (104) comprising hydrogen and nitrogen, a CC -rich stream (101), a process condensate (102), and at least one off-gas stream (151); an ammonia synthesis loop (200) arranged to receive the syngas stream (104) and to generate a first ammonia-rich stream (201).

2. The ammonia plant according to claim 1, wherein said steam drum (110) is arranged to receive at least the first steam stream (41) from said first waste heat boiler (40), , and optionally the second steam stream (71) from said second heat exchanger (70).

3. The ammonia plant according to any one of the preceding claims, wherein the second shift section is a low temperature (LT) or a medium temperature (MT) shift section, preferably a low temperature shift section.

4. The ammonia plant according to any one of the preceding claims, wherein said steam drum (110) is also arranged to receive at least the first steam stream (41) from said first waste heat boiler (40), the second steam stream (71) from said second heat exchanger (70) and - optionally - a third steam stream (114') from the loop heat exchanger (251), said ammonia plant further comprising a fired steam superheater (120) being arranged to receive a saturated steam stream (111) from said steam drum (110) and to superheat it to provide a superheated steam stream (121).

5. The ammonia plant according to any one of the preceding claims, wherein said ammonia plant does not comprise a fired steam superheater (120).

6. The ammonia plant according to any one of the preceding claims, comprising a fired heater (90) and a fuel stream (9) for said fired heater, wherein at least one - and preferablyall - of said feed pre-heater (91), prereformer feed preheater (92) and syngas pre-heater (93) comprise heater coil(s) within said fired heater (90).

7. The ammonia plant according to claim 6, wherein a portion of the syngas stream (104) comprising hydrogen and nitrogen is arranged to be fed as fuel to the fired heater (90) and / or the fired superheater (120).

8. The ammonia plant according to any one of the preceding claims, wherein the syngas purification section (100) comprises a separator (130), a CO2 removal unit (140) and a hydrogen purification unit (150).

9. The ammonia plant according to claim 8, wherein the separator (130) is arranged to receive said fourth process gas stream (61) and generate a dried fourth process gas stream (131) and a process condensate (102), wherein the CO2 removal unit (140) is arranged to receive said dried fourth process gas stream (131) and to generate a CCh-rich stream (101) and a CO2-depleted fourth process gas stream (141) and wherein the hydrogen purification unit (150) is arranged to receive the CC -depleted fourth process gas stream (141) and to generate the syngas stream (104) comprising hydrogen and nitrogen (suitably in a ratio of 3: 1) and an off-gas stream (151).

10. The ammonia plant according to claim 8, wherein the syngas purification section (100) comprises, in order: separator (130), hydrogen purification unit (150) and CO2 removal unit (140).

11. The ammonia plant according to any one of claims 8-10, wherein at least a first portion (151A) of the off-gas stream (151) is arranged to be compressed in a compressor (160) and combined with the first process gas stream (21), upstream the ATR. section (30).

12. The ammonia plant according to claim 11, wherein at least a second portion (151B) of off-gas stream (151) is arranged to be fed as fuel to the fired heater, optionally in combination with a portion (104A) of the syngas stream (104).

13. The ammonia plant according to any one of the preceding claims, wherein the ammonia synthesis loop (200) comprises an ammonia reactor (240), a recycle compressor (220), an ammonia separator (230) and at least one heat exchanger (250, 251) arranged downstream the ammonia reactor (240), wherein a third boiler water stream (114) is arranged to be heat exchanged in said at least one heat exchanger (251), comprising a waste heat boiler and optionally a steam superheater.

14. The ammonia plant according to any one of the preceding claims, wherein the feed pre-heater (91) is arranged to pre-heat the hydrocarbon feed (1) via heat exchange with at least a portion of the second steam stream (71) or a superheated steam stream (121, 115').

15. A process for generating ammonia in the ammonia plant (A) according to any one of the preceding claims, said process comprising the steps of: providing the plant according to any one of the preceding claims, pre-heating the hydrocarbon feed (1) in the feed pre-heater (91) and generating a pre-heated hydrocarbon feed (1'); hydrogenating and removing sulfur compounds from the preheated hydrocarbon feed (1') in the feed purification section (80), and generating a purified hydrocarbon feed (1"); heating a combined stream (81) comprising purified hydrocarbon feed (1") and process steam feed (2) in the prereformer feed preheater (92) and generating a heated combined stream (81'); pre-reform the heated combined stream (81') from the prereformer feed preheater (92) in the prereforming section (20) and generating a first process gas stream (21); heating the first process gas stream (21) in the syngas pre-heater (93) and generating a heated first process gas stream (21') feeding at least a portion of the heated first process gas stream (21'), said oxygen feed (3) and said burner steam feed (2') to the autothermal reforming ATR. section (30) and generating a second process gas stream (31); feeding boiler feed water (8) to the steam drum (110) supplying a first boiler water stream (112) and a second boiler water stream (113); heat exchanging at least a portion of the second process gas stream (31) with a first boiler water stream (112) from said steam drum (110) in the first waste heat boiler (40) and generating a cooled second process gas stream (31') and a first steam stream (41); feeding the cooled second process gas stream (31') from the first waste heat boiler (40) to the high temperature (HT) shift section (50) and generating a third process gas stream (51); heat exchanging at least a portion of the third process gas stream (51) with a second boiler water stream (113) from said steam drum (110) in the second waste heat boiler (70) and generating a cooled third process gas stream (51') and a second steam stream (71); and / or heat exchanging at least a portion of the third process gas stream (51) with a steam stream (115) from said steam drum (110) in the steam superheater (75) andgenerating a cooled third process gas stream (51') and a superheated steam stream (115'); provided that, when the ammonia plant comprises a second waste heat boiler (70) and a steam superheater (75), the third process gas stream (51) is fed to the steam superheater (75) and cooled to a third process gas stream (51') which is then fed to the second waste heat boiler (70) and cooled to a further cooled third process gas stream (51"); feeding the cooled third process gas stream(s) (51', 51") to the second shift section (60) and generating a fourth process gas stream (61); - feeding the fourth process gas stream (61) and said nitrogen feed (4) to the syngas purification section (100) and generating a syngas stream (104) comprising hydrogen and nitrogen (e.g. in the ratio 3: 1), a CCh-rich stream (101), a process condensate (102), and at least one off-gas stream (151); feeding the syngas stream (104) to the ammonia synthesis loop (200) and generating a first ammonia-rich stream (201).