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For valve designs in biogas plants or for upgrading biomethane and CO2, GEMÜ offers technically advanced solutions tailored to each process step.
Why GEMÜ?
Whether you are looking for robust globe valves for rapid switching cycles, butterfly valves for larger nominal sizes or ball valves for shutting off gas pipes, GEMÜ is the right choice. Thanks to our wide range of valve types and accessories, we provide comprehensive valves, measurement and control systems from a single source.
What you need to take into account when selecting valves
Biomethane purification often sees multiple methods combined in order to get the most out of the respective treatment steps. For example, this includes desulphurization through absorption (activated charcoal), drying through cooling through pressure swing adsorption (zeolite) and the method for removing CO2 explained further down.
Tips for selecting valves
| Application | Special operating parameters and requirements | What you need to consider when selecting valves |
|---|---|---|
| Gas scrubbers • Flow control • Temperature control | Desorption up to 100 °C, Chemical resistance against amines or Genosorb | For water: Stainless steel bodies and EPDM seals For amines/Genosorb®: Stainless steel bodies and PTFE seals |
| Membrane separation process • Pressure control | Up to 10 bar, ambient temperature | Cast bodies with NBR or PTFE seals, GEMÜ can assist with precisely designing control valves. Get in touch with us. |
| PSA systems | Frequent cycle duties and sometimes two-way flow | Often globe valves with actuators for high cycle duties Suitable valve types for two-way flow include butterfly and diaphragm valves |
Gas scrubbers can be operated with various media. In a pressurised water scrubber, the compressed biogas is cleaned with water. The CO2 is physically separated in the water (absorption) and can be driven out into a second column at lower pressure (desorption). The water can then be fed back to the absorption column.
In addition to water, polyglycols can also be used in physical gas scrubbing. Once the CO2 has been absorbed, the medium is also regenerated (usually by increasing the temperature) and is returned to the absorption column after it has cooled down.
This is where GEMÜ valves are used:
• Shut-off valves: For pumps and containers in order to isolate and drain media
• Control valves: For regulating the volume flow of the medium and, depending on the method, at the heat exchangers for temperature control
Metalkugleventil GEMÜ B20 (valgfrit: håndtag gul)
Angle seat globe valve GEMÜ 554
Diaphragm valve GEMÜ 695
The functional principle of PSA systems is adsorption followed by a pressure swing.
By transferring the gauge pressure between parallel adsorption tanks, continuous operation of the system is possible with high energy savings. During biomethane extraction, biogas flows into the purification tank. As a result, CO2 is selectively adsorbed by the molecular sieves. Purified biomethane flows out. The second tank is regenerated (vented and flushed out) and the CO2 is released into the surrounding environment. For continuous operation, both of the absorption tanks are operated alternately. While absorption is taking place in one tank, the other tank is regenerated. Before a sorption cycle starts, a pressure swing is performed. From the saturated tank, the pressurized gas is transferred to the regenerated tank.
Typical requirements for valve designs:
Frequent cycle duties, sometimes every minute: GEMÜ globe valves with actuators for high cycle duties are the right choice for these applications.
Two-way flow during a pressure swing: Butterfly valves or diaphragm valves are suitable valve types for this process because they do not have a specified flow direction due to the design.
Tugela metal butterfly valve GEMÜ R470
Global valve GEMÜ 534
Diaphragm valve GEMÜ 695
Gas purification with polymer diaphragms adopts the different permeation properties of the gases.
CO2 and H2S permeate through the diaphragms more easily than biomethane and can therefore be discharged. This produces high-purity biomethane.
You need to consider the following:
Since diaphragm systems usually have multiple layers, different pressure ratings need to be taken into account when selecting valve designs..
In addition to control valves, this method also includes many manual valves in the systems.
Metall ball valve GEMÜ B20 (optional: hand lever yellow)
Angle seat globe valve GEMÜ 550 (optional: special function G)
Metal butterfly valve GEMÜ R487 Victoria (optional: hand lever yellow)
Achieve synchronous and precise control results:
The wrong design of control valves can result in poor control results or premature wear. This is why GEMÜ places particular importance on the precise design of the control valves.
Our technical advisors technical advisors and specification sheet can help you to design control valves for your own applications.
For the reliability of your plant – approvals relating to gases
To ensure flawless handling of combustible gases, our valves comply with high safety standards, such as ATEX or SIL. Our range also includes valves with DVGW gas approval.
Application examples
❯ Gas purification
Pressure swing adsorption (PSA) is the general designation for a gas purification system based on selective adsorption. If biomethane needs to be prepared or refined on-site, PSA systems are a cost-effective and reliable option.
GEMÜ offers the ideal valve designs for this type of system. Read more about the application using the example of PSA systems here.
❯ Reusing digestate
Valuable raw materials, such as phosphate fertilizers, can be recovered from digestate left over after fermentation.
Read more on the application and which GEMÜ valves are suitable for these innovative recycling procedures here.