Selected steps can be eliminated
S-storage & dispatch
H SO sulphuric acid
H S
S-storage
Melting
Burning
Conversion
Re nery
Fertiliser
Conversion
Transportation of solid sulphur
H S can be directly converted to sulphuric acid
Figure 3 H₂S conversion to sulphuric acid
Integration setup Additionally, CO₂ present in flue gases from fired heaters, boilers, and process units like fluid catalytic cracking (FCC) and continuous catalytic reforming (CCR) can be recovered and utilised as a feedstock for fertiliser production. The availability of proven technologies such as amine scrub - bing, membrane separation, and cryogenic methods ena - bles efficient CO₂ extraction from refinery emissions. The captured CO₂ can then be used in producing urea and other nitrogen fertilisers, turning waste into valuable products. In a standalone fertiliser complex, NH₃ is typically synthe - sised using hydrogen (H₂) and nitrogen (N₂). H₂ is produced in the steam methane reformer (SMR), while N₂ is generated in the air separation unit (ASU). As mentioned earlier, inte - gration of refinery and petrochemicals will result in the avail - ability of surplus H₂, which can be used for NH₃ synthesis. Moreover, refinery and petrochemical complexes usually have their own N₂ generation unit, designed to accommo - date intermittent operations such as inertisation and catalyst regeneration. During normal operation, this results in surplus N₂, which can also be used for NH₃ production. Consequently, the availability of recovered NH₃ and surplus H₂ reduces the required capacity of the SMR in the integrated setup. Furthermore, direct conversion of H₂S to H₂SO₄ can elim - inate the need for a separate H₂SO₄ plant, which is typically required in standalone fertiliser facilities. Overall, integrating
the fertiliser complex with refinery and petrochemical opera - tions promotes a circular economy model by reducing waste disposal, valorising low-value waste streams, decreasing demand for fresh feedstocks, and lowering carbon emissions and resource consumption. Figure 4 shows a schematic flow diagram of such an integrated complex. Integration model The concept behind this integrated model is to unify refin - ery, petrochemical, and fertiliser plants into a single, seam - less operation. In such an integrated complex, boundaries between units are minimised, enabling smoother flow of materials and more efficient resource utilisation. The design aims to reduce costs compared to constructing sep - arate facilities while also lowering carbon emissions. This is achieved through several key strategies: • Integrated feedstock flow: Streams such as NH₃, H₂S, and CO₂ from the refinery and chemical units will be directly fed into the fertiliser section, eliminating the need for addi - tional storage or transporting these materials and reducing fresh feed requirements. • Optimised use of surplus materials: Surplus H₂ and N₂ will be utilised effectively, leading to a reduction in the capacity requirements of the SMR unit. Additionally, the direct conversion of H₂S to H₂SO₄ will negate the need for a separate H₂SO₄ plant.
• Shared utilities: The complex will employ common systems for generating steam, elec - tricity, and water, resulting in cost savings through reduced equipment redundancy and improved energy efficiency. • Joint waste treatment: Waste streams from differ - ent parts of the plant will be treated together, leading to better recovery of useful mate - rials and fewer emissions. • Shared infrastructure and logistics: The use of common infrastructure and logistics will decrease the required plot area and significantly reduce manpower for operations.
Need lower capacity reformer
Green H
NG/naphtha
H
Eliminated H SO unit Need lower capacity ASU
Steam cracker
Re nery
Reformer
Recovered CO
Aromatic complex
HGU
CO
H
H
Recovered NH
Spare capacity in HGU
Produced H SO
Fertiliser complex
H SO
Surplus H
N
N
ASU
Sulphuric acid plant
Surplus N
ASU
Margin available during normal operation
S
Figure 4 Schematic flow diagram when integrating fertiliser complex with refinery and petrochemical operations
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PTQ Q4 2026
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