Recycle Gas Compression Solutions

Many refining, petrochemical and chemical reactions do not convert the complete feed stream during a single pass through the process. After separation of the reaction products, unconverted gases can be recompressed and returned to the reactor or another upstream process stage.

Recycle gas compression helps maintain the required circulation rate, reactant concentration and reactor conditions. Depending on the process, it can improve feedstock utilization and support stable continuous operation. A controlled purge stream may still be necessary to prevent inert gases, impurities or unwanted components from accumulating in the recycle loop.

Recycle streams can contain Hydrogen (H₂), synthesis gas, hydrocarbons, Carbon Dioxide (CO₂), Nitrogen (N₂) and application-specific gas mixtures. Their composition may change between operating cases and can contain condensable or corrosive components that must be considered during compressor engineering.

The required compressor configuration depends on the gas composition, circulation rate, suction and discharge conditions, pressure ratio, temperature and expected operating range. Separation, cooling and process controls must be coordinated with the complete recycle loop.

With more than 80 years of experience in reciprocating high pressure compressor technology, LMF develops tailor-made recycle gas compressor solutions for continuous industrial processes. Every solution is individually engineered according to the process duty and applicable project specifications.

Recommended Compression Solutions by LMF

ISO 13631 Compressors

Recommended for continuous recycle gas applications requiring stable flow rates, flexible package engineering and reliable operation across the specified process range.

  • Capacity:
    up to 15 100 Nm³/h
  • Pressure:
    up to 301 bar
  • Power consumption:
    6 MW

API 618 Compressors

Recommended for demanding heavy-duty recycle gas services requiring high availability, continuous operation and project-specific engineering according to API 618.

  • Capacity:
    up to 27 000 Nm³/h
  • Pressure:
    up to 200 bar
  • Power consumption:
    6 MW

Selected References 

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FAQs

Recycle gas compression returns unconverted or reusable gas from a downstream separation stage to a reactor or another upstream process point. It forms part of a closed process loop designed for the respective chemical or refining process.

Applications include hydrogenation, hydroprocessing, hydrocracking, ammonia and methanol synthesis, Fischer–Tropsch synthesis and other catalytic processes involving continuous gas recirculation.

Not necessarily. A controlled purge may be required to prevent inert gases, impurities or unwanted by-products from accumulating within the recycle loop. The purge strategy is determined by the overall process design.

Changes in conversion rate, feed composition and separator performance can alter the recycle gas properties. These variations affect compressor capacity, power demand, discharge temperature, condensation behavior and material requirements.

Initial engineering requires the gas composition for every operating case, molecular weight, suction and discharge conditions, required circulation rate, temperature range, turndown requirements and details of potential liquids, contaminants or corrosive components.