Ammonia & Syngas

Synthesis gas (syngas) streams require molecular sieves, often downstream of other treatment units, to remove water and other contaminants to very low levels. This is required for protection against pressure drop and catalyst poisons that can cause plant performance to decline and catalyst deactivation. Contaminants can condense at lower temperatures and form solids in downstream equipment, leading to high pressure drop, loss of flow rate and ultimately lower plant efficiency. Thus, the molecular sieve ensures consistent, efficient and predictable performance over many years in between plant shutdowns and turnarounds.

The molecular sieve is typically being used to remove water, carbon dioxide, ammonia and sometimes oxygenates such as methanol, and various sulfur compounds. Synthesis gas is most often used to produce ammonia, methanol, higher hydrocarbons (synthetic fuels), hydrogen and dimethylether. In ammonia plants, the molecular sieve is primarily used to remove water in addition to trace ppmv-level carbon dioxide and ammonia from the syngas stream consisting mainly of nitrogen and hydrogen, with a small amount of methane.

Zeochem 4A and 13X molecular sieves are used in this service. Older-generation plants use 4A as it adequately removes water, carbon dioxide and ammonia. For older-generation plants seeking enhanced performance, newer-generation plants with reduced firing in the primary reforming furnace and cryogenic inert impurity removal, our 13X sieve is used.

Applications

Older-Generation Versus Newer-Generation Plants

Our Z4-01 molecular sieve is the standard grade of the 4A type zeolite that is used for dehydration of synthesis gas for the production of ammonia in plants currently using this product or in plants not utilizing cryogenic impurity removal. It effectively removes water, ammonia and carbon dioxide (CO2) from the feed stream. Z4-01 is normally regenerated at a temperature of 550 degrees Fahrenheit (288°C) with a typical range of 500-600°F (260-315°C).

The 13X molecular sieves provide enhanced capacity and performance for ammonia plant service and are the recommended products for all newer-generation plants. The 13X molecular sieve has significantly higher capacity for water, ammonia and CO2. These products have an open pore structure with 10 angstrom crystal pore openings, giving them optimum kinetics and dynamic performance ideally suited for ammonia plant service. Our 13X products normally regenerate at a temperature of 500-550°F (260-288°C) in this application, but the acceptable range is 450-600°F (232-315°C).

Related Products

Zeochem offers a broad range of molecular sieve products ideally suited to each natural gas, LNG and fractionation plant adsorbent application. From dehydration of natural gas to protect downstream cryogenic equipment to final sulfur and oxygenate removal from liquid hydrocarbon streams to meet product specifications, Zeochem products are specialized for reliable operation in a wide range of applications.

4A

4A is the sodium form of the type A zeolite molecular sieve and is widely used as a general purpose drying agent. Under certain conditions, it can also be used for removal of ammonia, alcohols, carbon dioxide, H2S and other specific molecules.

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13X

Type 13X offers enhanced adsorption properties and the ability to remove impurities too large to be adsorbed by the type A zeolites.

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Custom Solutions

Zeochem employs technical service engineers and scientists who have years of experience in adsorber design, operation and maintenance.

From the beginning of each project, our technical service engineers can provide conceptual advice and design support. As the project moves forward, we can review the detailed designs and procedures. We offer consultation on last-minute change orders and start-up assistance when the unit is to be commissioned. Follow-up service is available for troubleshooting and performance optimization.