Coal-based ammonia complexes:\nWhich gasifier type is most characteristically attached to coal-based fertiliser (ammonia) plants to generate pressurised synthesis gas?

Introduction / Context:
Coal-based fertiliser plants require synthesis gas (H2, CO, CO2) suitable for shift conversion and subsequent ammonia synthesis. The choice of gasifier affects pressure level, gas composition, tar handling, and downstream compression costs. This item targets recognition of the gasifier historically associated with coal-to-ammonia complexes.

Given Data / Assumptions:

• Objective: produce syngas for shift and H2 recovery at conditions compatible with large downstream compressors.
• Coal feed; reliability and ash handling are important.
• Traditional installations valued pressurised output to reduce compression duty.

Concept / Approach:
The Lurgi fixed-bed gasifier operates at elevated pressure and has long been paired with ammonia plants, easing integration by delivering gas at useful pressure. By contrast, the Kopper–Totzek (entrained-flow) process runs near atmospheric pressure and would require substantial downstream compression, which was historically less attractive in fertiliser service despite other merits (tar minimisation, high throughput). Thus, the characteristic choice is the Lurgi high-pressure design.

Step-by-Step Solution:

Verification / Alternative check:
Historical coal-to-ammonia complexes cite Lurgi-type units upstream of shift/CO2 removal, evidencing the pairing.

Why Other Options Are Wrong:

• Kopper–Totzek is atmospheric; compression penalty is large.
• Answers specifying only a pressure (20 or 40 atm) ignore reactor type and are incomplete.
• Fluidised-bed “without compression needs” is unrealistic; compression is still required for ammonia synthesis.

Common Pitfalls:
Equating gasifier choice solely with ash/slag handling; for fertiliser integration, delivery pressure is also pivotal.

Final Answer:
Lurgi high-pressure fixed-bed gasifier