Broad, Flexible Technology Portfolio Covering Just About All Gas Conditioning, Purification and Liquefaction Needs

The carbon monoxide (CO) shift conversion process is a vital tool in the drive to optimize hydrogen production from syngas. It is employed downstream of primary syngas production methods utilizing hydrocarbon feedstocks. The syngas typically consists of hydrogen (H₂), carbon monoxide (CO), carbon dioxide (CO₂), methane (CH₄), and water in chemical equilibrium at high temperatures ranging from 700 to 1400°C, depending on the process pressure, feedstock mixture, and the amount of process steam or water.

The CO shift conversion process repurposes a substantial portion of the CO content in the syngas, enhancing hydrogen (H₂) yield based on the equation below.

CO + H₂O ⇔ H₂ + CO₂

We offer three distinct versions of the CO shift process, each tailored to specific temperature ranges and hydrogen output goals.

1. High-temperature (HT) CO shift conversion:
   Operating between 300 and 450°C, this method reduces CO content to around 2.5% (dry basis) at the reactor outlet. It is the industry-standard solution for hydrogen generation and is widely implemented in hydrogen plants.
2. Medium-temperature (MT) CO shift conversion (isothermal):
   Running at temperatures between 220 and 270°C, this approach brings CO content down to approximately 0.5% (dry basis) at the reactor outlet, enabling greater hydrogen yields in scenarios requiring enhanced conversion efficiency.
3. Low-temperature (LT) CO shift conversion:
   Functioning within the 180 to 250°C range, LT shift conversion achieves exceptional CO reductions, down to as low as 0.2% (dry basis) at the reactor outlet. Typically installed downstream of a HT shift conversion for an additional hydrogen boost, this method is often utilized in high-capacity plants producing more than 40,000 Nm³/h of H₂.

Each CO shift variant is facilitated by specially engineered catalysts housed within fixed-bed reactors, ensuring high hydrogen yields and optimal performance. While HT shift conversion is a standard feature of nearly all hydrogen plants, the LT shift conversion serves as a powerful enhancement for plants requiring large-scale hydrogen production.

The isothermal CO shift reaction relies on our proprietary isothermal reactor. The fixed-bed reactor design with indirect heat exchange is suitable for endothermic and exothermic catalytic reactions. Not only does this design leverage the benefits of a tube reactor, it also avoids the heat tension problems of a straight tube reactor. The heating or cooling tube bundle embedded in the catalyst transfers the reaction heat in such a way that the catalyst can work at an optimum temperature. This results in higher outputs, a longer catalyst lifetime, fewer by-products as well as efficient recovery of the reaction heat and lower reaction costs. Gas/gas, gas/liquid and liquid/liquid reactions are supported.

The reactor design reflects the decades-long, market-leading experience we have gained designing and producing over 1000 coil - wound heat exchangers.

Thanks to our state-of-the-art technologies and proven expertise, all CO shift processes provide reliable, efficient and scalable solutions for boosting hydrogen output across different industrial applications, while offering the flexibility to meet the unique operational needs of high-demand facilities.

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Amine wash technology - also known as amine gas treatment or amine scrubbing - is a widely used method for removing carbon dioxide (CO₂) from flue gases in industries such as power generation, chemicals, cement and steel. This post-combustion capture (PCC) process is also commonly applied in natural gas processing, refineries and chemical plants to purify gas streams and meet CO₂ emission reduction targets.

In a typical PCC setup, a specially engineered plant uses an amine-based solvent to chemically absorb CO₂ from flue gases after combustion. The process begins in the absorber column, where flue gas enters from the bottom and flows upward counter-current to the descending aqueous amine solution. High-performance packing ensures efficient mass transfer while minimizing column diameter and pressure drop. The absorption reaction generates heat, reducing process efficiency. To counter this effect, a gravity-driven interstage cooler is installed to improve performance. The upper section of the absorber includes an advanced emission control system.

The desorber column regenerates the amine solvent. The CO₂-rich solution enters the top of the column and flows downward, counter-current to the steam generated in the reboiler. CO₂ is stripped from the solution and exits the column saturated with water vapor. This stream is cooled in an overhead condenser, where water and CO₂ are separated in a reflux drum. The condensate is returned to the column, and the steam condensate from the reboiler is sent back to the battery limit.

Captured CO₂ can be utilized commercially - for example, in the food and beverage industry, for enhanced oil recovery (EOR) or as a feedstock for methanol or urea production. Alternatively, it can be stored underground as a carbon abatement measure. We bring extensive experience in designing and constructing chemical wash systems, including amine-based solvent systems and CO₂ compression, drying and purification units. In collaboration with strategic partners like BASF, we offer comprehensive, end-to-end solutions.

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There are two main physical wash systems - an acid gas removal process and a liquid nitrogen wash process. These are described in more detail below.

Rectisol Wash

Rectisol is our physical acid gas removal process that uses an organic solvent, typically methanol, at sub-zero temperatures. It can purify synthesis gas to extremely low levels of total sulfur, including carbonyl sulfide (COS) and carbon dioxide (CO₂), down to 0.1 volume parts per million (vppm) and parts per million (ppm) ranges respectively.

The main advantages of Rectisol include its low utility consumption, the use of a cheap and readily available solvent, and its flexible process configuration. CO₂ and sulfur compounds are removed in separate fractions, resulting in a pure CO₂ product (useful for urea production) and a Claus gas fraction enriched in hydrogen sulfide (H₂S) and COS.

We have gained extensive design and operational experience in the integration of Rectisol in various upstream and downstream processes, particularly in the handling of trace components. Design highlights include our proven coil-wound heat exchangers, which enhance energy efficiency and plant economics.

Commercial-scale Rectisol wash units are successfully deployed around the world for purifying hydrogen (H₂), ammonia (NH₃) and methanol syngas, and for producing pure carbon monoxide (CO) and oxogases. Due to its physical nature, Rectisol is especially effective at high pressures and high sour gas concentrations. It is frequently used to purify shifted, partially shifted or unshifted gas downstream of residue oil, coal or lignite gasification. Additionally, its low operating temperature makes Rectisol favorable for cryogenic downstream processes, such as liquid nitrogen (LIN) washing and cryogenic recovery of CO and oxogas.

Liquid Nitrogen Washing

Ammonia (NH₃) production requires a synthesis gas with a precise nitrogen-to-hydrogen (N₂/H₂) ratio of 1:3. To ensure optimal reaction conditions, trace impurities such as methane (CH₄), argon (Ar) and carbon monoxide (CO) must be reduced to below 5 ppm, as these inert components can interfere with the synthesis process.

The liquid nitrogen wash process is typically the final purification step before ammonia synthesis, especially in fertilizer plants using coal or residue oil as feedstock. It is commonly installed downstream of a Rectisol scrubbing unit.

This process is housed in a prefabricated coldbox , which includes an upstream dryer unit. The coldbox is insulated with perlite and enclosed in a metal shell to minimize heat ingress. It is usually delivered to the site as a single assembled unit.

In the adsorber station, residual water, carbon dioxide and methanol (from upstream processes) are removed. The cryogenic separation equipment is located inside the coldbox.

During operation, raw H₂ and high-pressure N₂ are introduced into the unit and precooled against the outgoing product gas. H₂ enters at the bottom of the N₂ wash column, while liquid N₂ is introduced at the top. Trace impurities are separated and discharged as fuel gas. To achieve the required H₂/N₂ ratio, additional high-pressure N₂ is injected into the process stream.

We design and manufacture the cryogenic equipment required for this process and assemble it in coldboxes at our workshops. This means customers benefit from efficient transport and installation.

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Cryogenic processes such as partial condensation and liquid methane (CH₄) washing are employed to recover pure carbon monoxide (CO) and pure hydrogen (H₂) from gases produced by partial oxidation or catalytic reforming. CO is primarily used in the production of acetic acid, formic acid, polyurethane, polycarbonates and methylacrylates. The required CO purity varies according to specific needs and can be adjusted to lower residual H₂ and CH₄ content to the parts per million (ppm) range.

Two main cryogenic processes are used to separate CO from synthesis gas. These are outlined below.

• Partial condensation process: The partial condensation process involves cooling the synthesis gas to very low temperatures, causing the CO to condense while other gases remain in the vapor phase. This separation is achieved through a series of heat exchangers and separators. The condensed CO is then collected and purified further if necessary. This process is particularly effective for feed gases with high CO content and low CH₄ content.
• Methane scrubbing process: The methane wash process uses liquid CH₄ to absorb CO from the synthesis gas. In contact with CH₄, the feed gas selectively dissolves the CO while other gases remain in the vapor phase. The CO-rich liquid CH₄ is then separated and distilled to recover pure CO. This process is suitable for feed gases with higher CH₄ content and lower CO content.

For both processes, it is essential that the feed gas is completely free of water, CO₂ and other components that could freeze at low operational temperatures. Therefore, the process gas is initially dried using a molecular sieve adsorber station.

Feed gas from partial oxidation typically has a high pressure, high CO content and low CH₄ content, making it suitable for the partial condensation process. Conversely, gases from steam reforming have a lower pressure, lower CO content and higher CH₄ content, which makes the CH₄ wash process more appropriate. Both processes can be configured in various ways depending on the required product purity, recovery rate and presence of other impurities like nitrogen (N₂) and argon (Ar) in the feed gas.

The simplest condensation configuration includes an adsorber station, a coldbox containing plate-fin heat exchangers to precool the feed gas against product streams, a H₂ separator and a stripping column. Typically, a dry piston or integrally geared centrifugal compressor is used to compress carbon monoxide.

We manufacture and assemble all cryogenic equipment at our workshops and supply these plants as single packaged units. The adsorber station and other machinery, such as the CO compressor, liquid CH₄ pump and expansion turbine, are supplied separately and interconnected on site. The coldbox is insulated with perlite on site.

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Pressure swing adsorption (PSA) technology relies on the physical attachment of gas molecules to an adsorbent material. The strength of this interaction varies depending on the gas component, the type of adsorbent, the partial pressure of the gas and the operating temperature.

Highly volatile and low-polarity components like hydrogen (H₂) are nearly non-adsorbable, unlike molecules such as nitrogen (N₂), carbon monoxide (CO), carbon dioxide (CO₂), hydrocarbons and water vapor. Therefore, these impurities can be removed from a hydrogen-containing stream, resulting in the recovery of high-purity H₂.

The PSA process operates at a nearly constant temperature and utilizes alternating pressure and partial pressure to facilitate adsorption and desorption. Since no heating or cooling is necessary, the process can achieve short cycles lasting just a few minutes, making it a cost-effective method for removing large quantities of impurities.

Adsorption occurs at high pressure, typically between 10 and 40 bar, until the adsorbent material reaches its equilibrium loading. At this point, the adsorbent material can no longer adsorb additional gas and must be regenerated. Regeneration is achieved by reducing the pressure to just above atmospheric levels, which decreases the equilibrium loading and causes the impurities to desorb from the adsorbent material. The amount of impurities removed in one cycle is determined by the difference between the adsorption and desorption loadings. After regeneration, the pressure is increased back to the adsorption level, and the process begins again.

Our high-performance PSA plants offer exceptional H₂ recovery and purification rates from various hydrogen-rich streams, delivering purity levels up to 99.9999 mol%. They combine top-tier reliability, modular design for fast setup, and tailored solutions to meet specific industry needs. With virtually 100% availability and an optimized cost-performance balance, they are ideal for applications across refineries, petrochemicals, and more.

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Our HISELECT^® powered by Evonik absorption technology utilizes specially developed hollow-fiber polyimide membranes to separate gases. Use cases include natural gas processing, hydrogen (H₂) recovery from synthesis plants and off-gas recovery from refineries and chemical plants. These membranes function as semi-permeable barriers, driven by partial pressure differences, to separate the feed gas into a low-pressure permeate, which is rich in the gas to be removed or recovered (such as carbon dioxide (CO₂) or H₂), and a high-pressure retentate, which has a low content of these components.

The superior selectivity and high permeation rates of these membranes are designed for high recovery rates. This innovation alters the traditional design rules for membrane plants in many applications, leading to fewer and smaller membrane stages, reduced energy consumption and increased availability.

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Gas purification by scrubbing results in the enrichment of sour gas components in the regeneration gas of the scrubbing unit. Our CLINSULF^® sulfur recovery solution is a catalytic process that uses an reaction with oxygen (O₂)  to convert the hydrogen sulfide (H₂S) content of the regeneration gas into elemental sulfur.

The process is based on our isothermal reactor, which is filled with a suitable catalyst. CLINSULF^® DO (direct oxidation) and CLINSULF® Sub Dewpoint are the two process configurations typically deployed to process off-gas streams.

Hydrogen (H₂) liquefaction is a critical step in the move to develop commercially viable hydrogen-based energy systems as liquefied H₂ can be stored and transported safely and efficiently. The process involves compressing and cooling H₂ gas until it becomes a liquid at 20 K (-253°C). In liquid form, H₂ is significantly more compact and easier to manage than the gas phase. It can be stored at low pressure in specially insulated containers until it is transported or used. Notably, a single liquid H₂ trailer can replace four to eight truckloads of compressed H₂, greatly improving transport efficiency.

We have decades of experience in the construction of H₂ liquefaction systems.

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The carbon dioxide (CO₂) liquefaction process purifies and separates CO₂ from a gas mixture for use in various industrial applications.

First, the CO₂ gas is dried to remove water and impurities, then heated and vaporized in a reboiler before entering a distillation column. Inside the column, vaporized CO₂ cools and condenses on trays, separating from inert gases like nitrogen (N₂) and oxygen (O₂), which exit as vapor at the top. The condensed liquid CO₂ is collected at the bottom, stored in pressurized tanks, and transported by trucks, railway cars or ships. For gaseous applications, it can be re-pressurized and distributed via pipeline networks.

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