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EP-4580796-B1 - METHOD FOR REDUCING CARBON DIOXIDE EMISSIONS IN A UREA PLANT

EP4580796B1EP 4580796 B1EP4580796 B1EP 4580796B1EP-4580796-B1

Inventors

  • PORRO, Lino Giovanni
  • Versteele, Wim

Dates

Publication Date
20260506
Application Date
20230901

Claims (10)

  1. A urea-producing plant, comprising a first steam network (10), configured to receive high-pressure steam at a pressure of from 1.5 to 11 MPa, a second steam network (11), configured to receive low-pressure steam at a pressure of from 0.1 to 0.7 MPa, and a high-pressure carbamate condenser (5) configured to provide low-pressure steam to the second steam network (11), characterized in that the plant comprises a steam compressor (4) configured to receive steam from the high-pressure carbamate condenser (5) via the second steam network (11), to convert low-pressure steam at a pressure of from 0.1 to 0.7 MPa into high-pressure steam at a pressure of from 1.5 to 11 MPa, and to deliver the high-pressure steam to the first steam network (10).
  2. The urea-producing plant according to claim 1, wherein the plant comprises one or more high-pressure devices connected to the first steam network (10), these one or more high pressure devices being a high-pressure stripper (2) or a urea hydrolyzer.
  3. The urea-producing plant according to any one of claims 1 to 2, wherein the plant comprises one or more low-pressure devices (3) connected to the second steam network (11), in particular wherein these one or more low-pressure devices are selected from the group consisting of an evaporator, carbamate decomposer, desorber, steam ejector, steam turbine and carbamate condenser.
  4. The urea-producing plant according to any one of claims 1 to 3, wherein the steam compressor (4) is connected to a steam turbine (6), which is connected to the first steam network (10) and configured to provide power to the steam compressor (4).
  5. The urea-producing plant according to any one of claims 1 to 4, wherein the steam compressor (4) is a two-stage compressor.
  6. The urea-producing plant according to any one of claims 1 to 5, wherein the plant comprises a carbon dioxide compressor and a first electric motor connected to the carbon dioxide compressor and configured to provide power to the carbon dioxide compressor.
  7. The urea-producing plant according to any one of claims 1 to 6, wherein the plant comprises a second electric motor which is connected to and configured to provide power to the steam compressor (4).
  8. A method for reducing carbon-dioxide emissions of a urea-producing plant according to any one of claims 1 to 7, comprising the steps of: - providing low-pressure steam at a pressure of from 0.1 to 0.7 MPa from a high-pressure carbamate condenser (5) via a second steam network (11) to the steam compressor (4); - converting the low pressure-steam at a pressure from 0.1 to 0.7 MPa into high-pressure steam at a pressure of from 1.5 to 11 MPa by the steam compressor (4); - directing the high-pressure steam produced by the steam compressor (4) to a first steam network (10).
  9. A method according to claim 8, further comprising the steps of - providing low-pressure steam at a pressure from 0.1 to 0.7 MPa from the second steam network (11) to one or more low-pressure devices (3); - providing high-pressure steam at a pressure of from 1.5 to 11 MPa from the high-pressure steam network (10) to one or more high-pressure devices.
  10. The use of a steam compressor in a urea-producing plant according to any one of claims 1 to 7 for reducing the carbon dioxide emissions of the urea-producing plant.

Description

Field of the invention The present disclosure is related to the field of urea production. Background of the invention Urea (H2NCONH2) is the most common nitrogen-containing fertilizer used today. Global annual production is estimated to be around 200 million tons. In addition to the use as fertilizer, urea is also used in various chemical synthesis, and as a solution in diesel-powered vehicles to reduce nitrogen oxides emissions. Urea-producing plants may use different technologies, such as the Stamicarbon or Saipem process, but they all rely on the same basic principles. In the synthesis section of a urea-producing plant, ammonia, and carbon dioxide (CO2) are reacted under high pressure (above 130 bar) and high temperatures, to produce an aqueous solution comprising urea, ammonium carbamate, and free ammonia. This aqueous solution is then purified and concentrated to obtain a urea melt. The urea melt can be diluted to obtain a urea aqueous solution which may be used in selective catalytic or non-catalytic reduction systems, such as diesel exhaust fluid, mixed with other nutrient sources, such as ammonium nitrate, to obtain aqueous solutions of urea ammonium nitrate, or solidified into urea-containing solids, such as granules or prills. The production of urea requires the input of high amounts of energy, in particular due to the reaction equilibrium existing between the starting materials and the final product. In most urea plants, this energy is obtained by burning non-renewable energy sources, such as natural gas or oil, to heat up water and produce steam. However, this production of energy releases vast amounts of carbon dioxide, a greenhouse gas, into the atmosphere, and there is a constant requirement from authorities and clients to reduce emissions of carbon dioxide from urea production. EP3896031A1 (Casale, 2021) discloses a method for revamping an ammonia-urea plant wherein: the ammonia section is modernized to produce an extra amount of low pressure steam; the condensation stage of the high-pressure urea synthesis loop is modified to use part of the condensation heat of the urea stripper vapours to produce medium-pressure steam, said medium-pressure steam is fed to one or more steam users of the urea section, particularly for carbamate decomposition, the input of low-pressure steam to the urea section is balanced by importing the extra low-pressure steam produced in the ammonia section. EP3656759A1 (Casale, 2020) discloses a process for synthesis of urea from CO2and NH3wherein a steam flow (13) produced in the condenser (3) of a high-pressure synthesis loop is compressed to raise its pressure and temperature before using the steam as a heat source for a downstream step of the process.CN112197613 discloses a method and a device for recycling steam, which can be used for recycling low-pressure steam in amelamine production device, and increases a utilization value of a byproduct low-pressure steam of a urea washing tower of the melamine production device. Summary of the invention The present inventors have identified a new method to reduce carbon dioxide emissions in a urea plant and have designed a urea plant with reduced carbon dioxide emissions. The present disclosure provides a urea-producing plant comprising a first steam network, configured to receive high-pressure steam, a second steam network, configured to receive low-pressure steam, , and a high-pressure carbamate condenser configured to provide low-pressure steam to the second steam network, wherein the plant comprises a steam compressor configured to receive steam from the high-pressure carbamate condenser via the second steam network, to convert low-pressure steam into high-pressure steam and to deliver the high-pressure steam to the first steam network. In an aspect, the present disclosure provides a urea-producing plant, comprising a first steam network, configured to receive high-pressure steam at a pressure of from 1.5 to 11 MPa, a second steam network, configured to receive low-pressure steam at a pressure of from 0.1 to 0.7 MPa, and a high-pressure carbamate condenser configured to provide low-pressure steam to the second steam network, wherein the plant comprises a steam compressor configured to receive steam from the high-pressure carbamate condenser via the second steam network, to convert low-pressure steam at a pressure of from 0.1 to 0.7 MPa into high-pressure steam at a pressure of from 1.5 to 11 MPa, and to deliver the high-pressure steam to the first steam network. The present disclosure also provides a method for reducing carbon dioxide emissions from a urea-producing plant according to the present disclosure, comprising the steps of: providing low-pressure steam from a high-pressure carbamate condenser via the second steam network to the steam compressor;converting the low-pressure steam into high pressure steam in the steam compressor;directing this high-pressure steam to the first steam network. In an aspect, the prese