popup arrow pop connector1 pop connector2 pop connector3
Selas Fluid
A Member of the Linde
Engineering Division
Five Sentry Parkway East
Blue Bell,
PA 19422
United States
Phone: 610-834-0300
Fax: 610-834-0473
www.selasfluid.com

Steam Hydrocarbon Reforming

With over 1 Billion cu.ft. per day of reformer capacity supplied in the last 5 years, Selas Fluid is your Hydrogen Headquarters.

In the steam reforming process, a light hydrocarbon feedstock (such as natural gas, refinery gas, LNG, or naphtha) is reacted with steam at elevated temperatures (typically 700° C to 900° C), and elevated pressures (15 to 31 bar) in nickel-based catalyst filled tubes to produce a synthesis gas. This gas consists primarily of hydrogen and carbon monoxide, but other gases such as carbon dioxide and nitrogen, as well as water vapor are also present. The typical ratio of this gas exiting the reformer is approximately 50% hydrogen, 10% carbon monoxide, with the balance being the other gases. Increasing the amount of steam used in the reaction will increase the hydrocarbon conversion rate, but the economic cost of the steam must be taken into account in the overall process. The typical steam to carbon ratio falls in the range of 2.8 to 3.2 to 1. The primary reforming reaction is:

CH4 + H2O -> 3H2 + CO, which is highly endothermic.


Collection ManifoldTo overcome the endothermic reaction, the catalyst filled tubes are heated from the combustion of fuels such as natural gas, plant gas, and PSA purge gas. In the common top fired reformer these fuels are burned in multiple low NOx burners that are mounted in the arch between adjacent rows of catalyst tubes, and fire downward. The sensible heat from the hot combustion gases is transferred from the outer surface of the tubes to the reaction that is taking place inside the tubes. With the top fired burner arrangement, the highest heat fluxes occur at the top of the catalyst tubes where there endothermic reaction begins, and the flue gas flows co-current with the reforming process. The hot synthesis gas exits at the bottom of the catalyst tubes, and is collected in a manifold that is below the reformer. This gas is then passed through a process gas boiler to generate steam. The combustion flue gas also exits at the bottom of the reformer, and passes through a waste heat recovery section that preheats the feed and also generates steam. The diagram at left depicts the top fired reformer, showing the burners and catalyst tubes.




 

Steam Hydrocarbon Reformers - Technology

Selas Fluid's hydrogen reformer process design is performed by a proprietary incremental kinetic model that was developed in-house, and refined with the data from over fifty years of operating experience. This model predicts the reforming process for a variety of feed stocks, and reformer configurations (such as top fired, wall fired, or floor fired). Our top fired design combines both process and physical arrangement benefits to minimize the total cost of ownership.


Advantages of the top fired design include:

  • Allowance for either modularized or stick-built construction to take advantage of the relative differences in shop assembly vs. field construction costs.
  • Compact firebox with fewer burners relative to the number of tubes. The smaller surface area per unit volume when compared with wall fired reformers minimizes heat loss and reduces construction time.
  • Single operating level of burners allows easy access and simplified combustion control.
  • Allowance for the use of horizontal or vertical heat recovery section to match plot space requirements.
  • Maximum reforming efficiency by achieving the highest heat flux at the location of the highest endothermic reaction (the upper one-third length of the catalyst tube).

Reformers
From initial three-dimensional design model to the finished product: the design tools utilized by Selas Fluid allow our clients to progressively visualize the reformer as it is designed.


Optimization of the reformer with the waste heat recovery section can be tailored to suit multiple design cases for varying feed stock, fuels, and steam requirements. The use of computational fluid dynamic (CFD) modeling and 3-dimensional design programs integrates the process design and the physical layout.
 

Steam Hydrocarbon Reformers - History

Selas Fluid was the first independent heater supplier to design, construct, and offer process guarantees for reforming furnaces in the United States. Our first reformer was supplied for an ammonia plant application in 1957. Prior to 1957, the majority of ammonia plants were supplied by process licensors; (Chemico, Girdler, and Kellogg). Each company had its' own proprietary reforming furnace design. Selas Fluid’s emergence as a supplier of the reforming technology was instrumental in enabling contractors such as C.F. Braun, Fluor, Bechtel, Pritchard, and Badger to enter the ammonia plant construction business. In 1959, we received our first patent for our reforming furnace technology. This patent was based on the Selas Gradiation® concept, which provided a uniform temperature profile around the catalyst tubes through a series of wall fired burners.

In 1962, Selas became the first independent reformer supplier to receive a direct license from ICI, Ltd. for their steam naphtha reforming process. Selas designed and supplied more than 30 steam-naphtha reformers, including the first 7 naphtha feed reformers in North America. As demand for hydrogen increased in the 1970’s, so did requirements for increased hydrogen purity. This in turn led to higher operating temperatures and pressures in the reformer, and evolutionary changes in the reformer design to accommodate the increased parameters.

As global energy costs soared in the mid-1970’s, the need for greater energy efficient designs also influenced reformer design. Selas Fluid's in-the-box outlet header design reduced the number of openings in the reformer and enabled operation at lower excess air ratios. The waste heat recovery section was optimized to include multiple stages such as feed preheat, superheated steam production, boiler feed water preheat, and combustion air preheat to maximize energy efficiency.

With the acquisition of Selas in 1982, Linde AG became the only hydrogen supplier to this day who owns both reforming and purification technologies. This allows for the total integration and optimization of the entire hydrogen plant, from feed pretreatment through purification.


Reformer Scope
Selas Fluid designs and supplies the reformer “island” that includes both the reformer and the heat recovery system for integration in a Linde-supplied hydrogen plant.

100MM SCFD reformer and waste heat recovery section supplied by Selas Fluid
100MM SCFD reformer and waste heat recovery section supplied by Selas Fluid in a hydrogen plant designed, supplied, and constructed by Linde. The pressure swing absorption (PSA) and feed pre-treatment systems are also depicted.

As global environmental regulations of the 1990’s required more stringent emission control, Selas integrated the latest in low NOx burner design with post combustion emission reduction technologies (such as selective catalytic reduction) to meet single digit NOx, CO, and NH3 emission standards. Our current reformer designs combine the experience gained from supplying over 300 reformers with the latest design tools in 3-D design, computational fluid dynamic modeling, and incremental kinetic modeling.

Reformer SCR Catalyst Diagram
Three-dimensional snapshot of the SCR catalyst module in the waste heat recovery section of a 100MM SCFD reformer
 

Steam Hydrocarbon Reformers - Experience Summary

Selas Fluid's experience includes the supply of over 300 reforming furnaces since 1957. These reformers are used in the production of ammonia, hydrogen, methanol, and synthesis gas. Our reformers are designed for a variety of feed stocks ranging from natural gas through naphtha. Typically our reformers are furnished with top mounted, down fired burners, which is the most cost effective and energy efficient design. However, customer requirements may dictate the use of multiple rows of radiant wall burners (the Selas Fluid Gradiation® design), or large capacity floor / shelf burners. Our reformers range in size from approximately 10 MM SCFD (11,200 Nm3) to over 120 MM SCFD (134,000 Nm3) capacities.

Services offered by Selas Fluid include:

  • Concept studies
  • Detail engineering, procurement, fabrication
  • Field construction
  • Commissioning and operator training
  • Upgrades for increased performance
  • Replacement of tubes, manifolds, burners, and other parts
  • goto topTop

    Steam Hydrocarbon Reformers

    Website Finder
    Other Linde websites are available from the drop-down menu below.