SYSTEM AND METHOD FOR PRODUCING GREEN UREA

Abstract

An apparatus for synthesizing urea comprises an ammonia source, a urea synthesis unit, wherein the ammonia source is connected to the urea synthesis unit via a reactant conduit, and an ammonia gas turbine, wherein the ammonia source is connected to the ammonia gas turbine via a fuel conduit and the ammonia gas turbine is connected to the urea synthesis unit via a steam conduit.

Claims

1-7. (canceled)

8. An apparatus for synthesizing urea, comprising: an ammonia source; a urea synthesis unit, wherein the ammonia source is connected to the urea synthesis unit via a reactant conduit; and ammonia gas turbine, wherein the ammonia source is connected to the ammonia gas turbine via a fuel conduit and the ammonia gas turbine is connected to the urea synthesis unit via a steam conduit.

9. The apparatus as claimed in claim 8, wherein the ammonia gas turbine is designed to drive a CO.sub.2 compressor.

10. The apparatus as claimed in claim 8, wherein the ammonia gas turbine is connected in a force-fitting manner to a generator, the generator being electrically connected to the urea synthesis unit.

11. The apparatus as claimed in claim 10, wherein the generator is electrically connected to the CO.sub.2 compressor.

12. The apparatus as claimed in claim 8, wherein the ammonia gas turbine is connected in a force-fitting manner to the CO.sub.2 compressor.

13. The apparatus as claimed in claim 8, further comprising a thermal splitting apparatus, the thermal splitting apparatus being designed for converting ammonia into hydrogen and nitrogen, wherein the thermal splitting apparatus is connected to the ammonia source and wherein the thermal splitting apparatus is connected to the ammonia gas turbine.

14. The apparatus as claimed in claim 13, wherein the ammonia gas turbine is connected to the thermal splitting apparatus via a heat conduit.

Description

[0029] The apparatus according to the invention is more particularly elucidated hereinbelow with reference to exemplary embodiments shown in the drawings.

[0030] FIG. 1: First embodiment

[0031] FIG. 2: Second embodiment

[0032] FIG. 3: Third embodiment

[0033] FIG. 1 shows a first embodiment of the apparatus according to the invention. The apparatus is preferably located close to a suitable CO.sub.2 source 80. The CO.sub.2 source 80 can for example be a waste incineration plant, a biogas plant or a direct air-capture process. Since the ammonia produced for the production of green urea is not specifically being produced from natural gas, the CO.sub.2 source is not, as was formerly the case, an ammonia synthesis apparatus. The apparatus further includes an ammonia source 10. The ammonia source 10 can theoretically be an ammonia synthesis apparatus. However, the latter makes sense only if there is sufficient renewable energy for the production of green ammonia at this site as well as a suitable CO.sub.2 source 80 for urea production. This cannot however be assumed in all cases; on the contrary, it is to be expected that this will not be the case. Ammonia will consequently be transported from the ammonia synthesis apparatus to users, for example the apparatus according to the invention. The ammonia source 10 can therefore also be a storage tank or a connection to an ammonia pipeline.

[0034] Ammonia is supplied from the ammonia source 10 to the urea synthesis unit 20 via a reactant conduit 30. Similarly, the carbon dioxide from the CO2 source 80 is supplied to an apparatus of the urea synthesis unit 20 via a CO.sub.2 compressor 70 in which the carbon dioxide is brought to the pressure required for urea synthesis. In the urea synthesis unit 20, carbon dioxide and ammonia are reacted to form urea. The urea exits the urea synthesis unit 20 as product and is supplied, for example, to a granulation apparatus, optionally after first being mixed with other components.

[0035] To provide the necessary energy, the apparatus includes an ammonia gas turbine 40. The ammonia gas turbine 40 is connected to the ammonia source 10 via a fuel conduit 50. If it is green ammonia produced in the ammonia gas turbine 40 that is being reacted, the energy thus generated will likewise be CO.sub.2 emissions-free. When ammonia is burned, only nitrogen and water are formed and released into the environment.

[0036] The ammonia gas turbine 40 is connected in a force-fitting manner to the CO.sub.2 compressor 70, more particularly they are both arranged on the same shaft, which may optionally include a gearbox. As a result, the ammonia gas turbine 40 drives the CO.sub.2 compressor 70 directly. At the same time, the waste heat generated in the ammonia gas turbine 40 is utilized to produce steam in a downstream heat exchanger, which is supplied to the urea synthesis unit 20 via a steam conduit 60. In this case, the steam can also come from a heat exchanger downstream of the actual combustion process.

[0037] As shown here, the ammonia gas turbine 40 can optionally additionally also be connected in a force-fitting manner to a generator 90. The electrical energy generated therein can be provided to the urea synthesis unit 20 via an electrical connection 100.

[0038] FIG. 2 shows a second embodiment that, in addition to the first embodiment, includes a thermal splitting apparatus 110. The thermal splitting apparatus 110 is fed with the waste heat of the ammonia gas turbine 40 via a heat conduit 120. A portion of the ammonia from the ammonia source 10 is supplied to the thermal splitting apparatus 110 and the mixture of ammonia, hydrogen and nitrogen produced is supplied to the ammonia gas turbine 40. The additional hydrogen results in more stable combustion in the ammonia gas turbine 40.

[0039] FIG. 3 shows a third embodiment, which differs from the first embodiment shown in FIG. 1 in that the ammonia gas turbine 40 is only connected in a force-fitting manner to the generator 90, more particularly is arranged on the same shaft. The generator 90 is connected via an electrical connection to the CO.sub.2 compressor 70, which is accordingly operated purely electrically. The advantage of this embodiment is the optimal operating mode of the ammonia gas turbine 40 for the generator 90, which makes it easier to respond to a fluctuating electricity requirement, for example in the urea synthesis unit 20, and to respond independently of the CO.sub.2 gas flow to be compressed.

Reference Signs

[0040] 10 Ammonia source [0041] 20 Urea synthesis unit [0042] 30 Reactant conduit [0043] 40 Ammonia gas turbine [0044] 50 Fuel conduit [0045] 60 Steam conduit [0046] 70 CO.sub.2 compressor [0047] 80 CO.sub.2 source [0048] 90 Generator [0049] 100 Electrical connection [0050] 110 Thermal splitting apparatus [0051] 120 Heat conduction [0052] 130 Product outlet [0053] 140 Off-gas