PURIFIERplus™ Ammonia Process

Commercial Applications

KBR's PURIFIERplus™ ammonia process combines proven and reliable technologies for the manufacturing of ammonia from our proprietary KRES™ (KBR Reforming Exchanger System), Purifier™ and horizontal ammonia synthesis converter to produce a synergistic, lower cost process that eliminates the need for an air separation plant and a primary reformer.

Values and Benefits

While KRES™ and Purifier™ provide significant cost savings and operational efficiencies separately, combining them in PURIFIERplus™ allows for further economic gains. The benefits of the Purifier™ process include:

• Reduced capital costs – Replacing the primary reformer unit with a KRES unit may provide up to 5 percent savings in up-front plant capital costs. Significant capital costs are also realized by eliminating air separation and purge gas recovery facilities.
• Reduced energy requirements – Fewer burners are necessary in the fired heater, resulting in lower process temperatures. Purifier provides higher loop conversion with low inerts.
• Reduced plot space – A 25-35% smaller footprint is required for the reforming section of the plant compared to conventional processes.
• Improved reliability and flexibility – The reforming exchanger is more reliable than a conventional reformer, and the simple and precise hydrogen to nitrogen ratio control stabilizes the entire plant operation. For locations subject to feed curtailments in winter months, KBR's KRES™ reforming system handles feed rate changes with little operator intervention and allows more expensive natural gas feed to be converted into syngas rather than used for fuel gas or steam generation.
• Improved environmental compliance – The system reduces CO₂ and NOx emissions.

Technology Information

KRES™

KRES™ is a proprietary heat exchanger-based steam reforming technology consisting of a fired preheater, an autothermal reformer (ATR) and a reforming exchanger. KRES™ takes the place of a conventional primary reformer by feeding excess air, natural gas feed and steam to the ATR and feed and steam in parallel into the upper end of the robust, shell-and-tube reforming exchanger. The compact ATR and reforming exchanger in combination with the fired preheater take up much less plot space than a conventional fired steam methane reformer.

The tubes in the KBR reforming exchanger are open-ended and hang from a single tube sheet at the inlet cold end to minimize expansion problems. They are packed with a conventional reforming catalyst, which can be easily loaded through a removable top head. The tubes are accessible and removable as a bundle for maintenance. This simple, proprietary design has proven to be extremely reliable and maintenance-free in commercial operation since 1994.

Read more about KBR Reforming Exchanger System (KRES™).

Purifier™

Downstream of the KRES™ unit, KBR's cryogenic Purifier™ process simultaneously removes impurities and adjusts the hydrogen to nitrogen ratio to 3:1. The system accepts purge gas from upstream, thus eliminating the need for a separate purge gas recovery unit.

The Purifier™ system consists of:

• A feed/effluent exchanger, plate fin-type design and constructed from aluminum
• A column that operates in the range of minus 170°C to minus 200°C, with a built-in condenser of shell and tube design
• A compact, low-speed expander that is typically sized for cool down and is coupled to a generator brake

All items and the connecting piping are welded and enclosed in a perlite-insulated cold box.

KBR proprietary cryogenic purification technology removes methane, argon and excess nitrogen from synthesis gas and allows use of air instead of oxygen in the reforming section of the ammonia plant, eliminating the need for an expensive air separation unit.

Read more about KBR's Purifier™ Cryogenic Syngas Purification.

Horizontal 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 vessel on tracks, thus avoiding the need for a heavy, expensive crane.

Read more about KBR's Horizontal Synthesis Converter.