Purifier™ Ammonia Process

Commercial Applications

KBR's Purifier™ Ammonia Process combines the following proprietary technologies to yield an extremely reliable, robust, low-energy plant:

• Mild reforming with excess air
• KBR Purifier
• Magnetite ammonia synthesis in a horizontal converter

With KBR's cryogenic Purifier™ syngas technology, you receive a lower-cost, more robust processing route to high-purity synthesis gas in ammonia manufacturing plants. The proprietary, front-end process cryogenic purification technology simultaneously removes impurities (i.e., methane, argon) from synthesis gas by washing it with excess nitrogen while adjusting the hydrogen to nitrogen (H2/N2) ratio to 3:1.

Values and Benefits

Providing a clean, dry, make-up gas to the synthesis loop and simple and precise H2/N2 ratio control, Purifier technology offers benefits to the entire operation in several key areas:

Low Energy Consumption

• A clean, dry make-up gas reduces the load on the synloop compressor and refrigeration systems, providing operational cost savings
• Mild reforming temperatures are used as methane slip is unimportant, which reduces fuel consumption and increases tube life
• Higher loop conversion is achieved with low inerts
• Purifier™ plants operate at some of the lowest proven energy consumption; a recent plant achieved an energy consumption of 6.5 Gcal/MT(ISBL, LHV basis)

Reduced Capital Costs

• No separate purge gas recovery unit is needed because purge gas rejected from the synloop is passed through the Purifier™ unit
• Very clean make-up gas provided by KBR's Purifier™ process lowers synthesis pressure, catalyst volume and purge rate, which means that smaller synloop equipment can be used

Flexibility

• Achieves greater stability and flexibility of operation, since the reforming section does not need to be tightly controlled to produce a precise H2/N2 ratio
• Maintains production even in the event of catalyst deactivation upstream of the Purifier™

Reliability

• Low reforming temperatures translate to lower stresses in and longer life of reformer tubes
• Numerous Purifier plants have run 3 - 4 years without a maintenance shutdown

Technology Information

Purifier™

The Purifier™ process system is a simple design consisting of three pieces of equipment: a feed/effluent exchanger, a column with a built-in condenser and an expander. All items and the connecting piping are welded and enclosed in a perlite-insulated cold box. Specific equipment design features include:

• Exchanger, which is a plate-fin design and constructed of aluminum
• Cryogenic column, which operates in the range of minus 170°C to minus 200°C
• Integral condenser, which is a shell-and-tube design
• Expander, which is a compact, low-speed unit that is typically coupled to a generator to recover power. A 2000 metric ton per day (MTPD) ammonia plant requires an expander with a capacity of about 200 kW.

Read more about KBR's Purifier Cryogenic Syngas Purification.

Horizontal Ammonia Synthesis Converter

For conventional magnetite ammonia synthesis loops, KBR offers its horizontal ammonia synthesis converter. The converter contains two or three reaction stages, each with vertical downward flow in the magnetite catalyst beds. Intercoolers are provided between the catalyst beds for maximum conversion and heat recovery.

The catalyst basket is easily removed from the converter shell for catalyst loading and unloading. The basket can be rolled out of the horizontal converter vessels on tracks, thus avoiding the need for scheduling and erecting a heavy and expensive crane for periodic maintenance.

Read more about KBR's Horizontal Ammonia Synthesis Converter.

Vertical Ammonia Synthesis Converter

If desired or required for a given project, KBR can provide the Magnetite ammonia synthesis converter in a vertical configuration to minimize plot space requirements.